MATERIALS AND METHODS RELATING TO IDENTIFYING INOSITOLPHOSPHOGLYCAN MIMETICS

Abstract: Methods for determining a binding profile for an inositolphosphoglycan (IPG) or a candidate mimetic compound are disclosed in which the IPG or candidate mimetic compound is contacted with an anti-IPG antibody in a binding assay and the binding of the IPG or candidate mimetic compound to the antibody is used to establish the binding profiles. The profiles are then used in methods for identifying candidate compounds for further testing or development as IPG mimetics.

Description: Materials and Methods Relating to Identifying Inositolphosphoglycan Mimβtics Field of the Invention The present invention relates to materials and methods for screening for inositolphosphoglycan (IPG) mimetics, and in particular to methods employing antibodies capable of specifically binding to inositolphosphoglycans (IPGs) . Background of the Invention Many of the actions of growth factors on cells are thought to be mediated by a family of inositol phosphoglycan (IPG) second messengers (Rademacher et al, 1994) . It is thought that the source of IPGs is a "free" form of glycosyl phosphatidylinositol (GPI) situated in cell membranes . IPGs are thought to be released by the action of phosphatidylinositol-specific phospholipases following ligation of growth factors to receptors on the cell surface. There is evidence that IPGs mediate the action of a large number of growth factors including insulin, nerve growth factor, hepatocyte growth factor, insulin- like growth factor I (IGF-I) , fibroblast growth factor, transforming growth factor β, the action of IL-2 on B-cells and T-cells, ACTH signalling of adrenocortical cells, IgE, FSH and hCG stimulation of granulosa cells, thyrotropin stimulation of thyroid cells, cell proliferation in the early developing ear and rat mammary gland. Soluble IPG fractions have been obtained from a variety of animal tissues including rat tissues (liver, kidney, muscle brain, adipose, heart) and bovine liver. IPG biological activity has also been detected in malaria parasitized red blood cells (RBC) and mycobacteria. We have divided the family of IPG second messengers into distinct A and P-type subfamilies on the basis of their biological activities. In the rat, release of the A and P-type mediators has been shown to be tissue-specific (Kunjara et al, 1995) . There are some references in the prior art to the production of polyclonal antibodies having anti-IPG specificity (see Romero et al, 1990; Huang et al, 1993; Nestler et al, 1991; Represa et al, 1991) . In these papers, a single polyclonal antibody is described which was raised against the GPI-anchor of the variant surface protein (VSG) of Trypanosoma brucei . The authors were forced to use this cross -reacting antigen for obtaining anti-IPG antibodies as soluble IPGs had not been purified and characterised, and so were not available for raising specific anti-IPG antibodies directly. The polyclonal antibodies produced using this immunisation protocol react also with the GPI-anchor moieties of GPI -anchor containing proteins. The papers report that this polyclonal antibody inhibits the action of insulin on human placental steroidogenesis, inhibits the action of insulin on muscle cells, inhibits the action of insulin on rat diaphragm and inhibits the action of nerve growth factor on chick cochleovestibular ganglia (CVG) . Summary of the Invention Broadly, the present invention relates to the use of polyclonal or monoclonal antibodies specific for inositolphosphoglycans (IPGs) in identifying compounds having one or more of the biological activities of a P or A- type IPG. We have previously found and isolated families of P and A-type IPGs, and shown that some of their activities are tissue specific. This tissue specificity could be advantageous in employing the IPGs as pharmaceuticals as they are likely to have very selective biological properties when administered in vivo. However, in instances where the IPGs themselves are difficult to isolate from natural sources in large quantities or are difficult to synthesise, it may instead be desirable to use a mimetic compound having the same or a similar activity that is easier to make or obtain. The closely related biological activities of the IPGs then become a problem in screening for such candidate mimetic compounds, as many conventional approaches to screening will not be able to differentiate the subtle differences in biological activity of different IPGs. By way of example, some mimetic compounds have already been found and are described in PCT/GB98/03837. This application discloses that compound C3, 1D-6-0- (2-amino- 2-deoxy-α-D-glucopyranosyl) -myo-inositol 1,2- (cyclic phosphate) , promotes neuron proliferation as do A- type IPGs, and compound C4, 1D-6-0- (2-amino-2-deoxy-α-D- glucopyranosyl) -chiro-inositol 1 -phosphate, promotes neurite growth as do P-type IPGs. The present invention approaches the problem of screening for IPG mimetics by taking advantage of the generation of a range of anti-IPG antibodies specific for a variety of epitopes on the IPGs. Accordingly, it is possible to use these antibodies to characterise the IPGs in the families, providing a "fingerprint" or binding profile that can distinguish a given IPG from other family members. This opens up the possibility of using the antibodies and the binding profiles to screen for IPG mimetics having an activity of a specific IPG, e.g. the activity of P-type IPG from placenta. This is especially useful as it simplifies the screening of candidate compounds, identifying lead compounds that are likely to have a specific IPG biological activity. The method has the further advantages in that it is not necessary to structurally characterise the IPGs or the candidate compounds, provided that the IPGs are isolated in a sufficiently pure form to raise the group of antibodies, and that it is amenable to high throughput screening (HTS) . The method could also be used to provide a stringent selection of reactive clones against a specific IPGs. Accordingly, in a first aspect, the present invention provides a method for determining a binding profile for an inositolphosphoglycan (IPG) or a candidate mimetic compound, the method comprising contacting the IPG or candidate mimetic compound with an anti-IPG antibody in a binding assay and determining the binding of the IPG or candidate mimetic compound to the antibody to provide the binding profile. In some embodiments, the binding profile comprises the results of binding assays in which more than one IPG or candidate mimetic compound is contacted with a given anti-IPG antibody. Alternatively or additionally, the binding profile comprises the results of binding assays in which more than one anti-IPG antibody is contacted with the IPGs or candidate mimetic compounds. in a further aspect, the present invention provides a method for identifying inositolphosphoglycan (IPG) mimetics, the method comprising: (a) contacting a P or A- type IPG with an anti-IPG antibody in a binding assay and determining the binding of the IPG to the antibody to provide a binding profile for the IPG; (b) contacting one or more candidate mimetic compounds with the anti-IPG antibody in a binding assay and determining the binding of the candidate mimetic compounds to the antibody to provide binding profiles for the candidate mimetic compounds; and, (c) comparing the binding profiles of the IPG and candidate mimetic compounds to identify for candidate mimetic compounds likely to have the IPG activity. In a further aspect, the present invention provides a method for screening for inositolphosphoglycan (IPG) mimetics, the method comprising having contacted a P or A- type IPG with an anti-IPG antibody in a binding assay to determine a binding profile for the IPG, the further steps of: (a) contacting one or more candidate mimetic compounds with the anti-IPG antibody in a binding assay and determining the binding of the candidate mimetic compounds to the antibody to provide the binding profiles for the candidate mimetic compounds; and, (b) comparing the binding profiles of the IPG and candidate mimetic compounds to identify candidate mimetic compounds likely to have given IPG activity. In the above methods, preferably, the method further comprises the step of testing a candidate mimetic compound identified in the method to determine whether it has a desired IPG activity. Thus, in these aspects of the invention the exposure of one or more antibodies to individual P or A- type IPGs provides binding profile (s) which can be used as a tool to screen a library of candidate compounds to identify candidate compounds likely to have given IPG activity. In the present invention, a "binding profile" is defined as the response (s) obtained when an IPG or a candidate mimetic compound is used in one or more binding assays employing one or more anti-IPG antibodies as binding agent (s). Such responses may be recorded simply as positive or negative, or the magnitude of the response may be determined, either to provide a value representative of the response or determine whether, within the limits of experimental error, the response is above a threshold value. In general, the binding profile will depend on the binding agent (anti-IPG antibody) or developing agent used and/or the conditions used to carry out the assay. The discrimination between different IPGs and candidate compounds that the binding profile provides will generally increase as the number of individual assays comprising the profile increases and as the precision of the determination of the response in the assays increases. In the present invention, the candidate compounds selected in the screen may be those have identical or near identical binding profiles to the given IPG, or in a less stringent screen, candidate compounds having similar binding profiles could be selected (e.g. preferably to within 20%, or more preferably to within 10%, or still more preferably to within 5% of the value obtained in a binding assay using the IPG) . Further, the selectivity of the screening method can be changed by altering the stringency in the determination of the binding profiles of the IPGs and/or in the stringency of the conditions used to screen for mimetics. This could be done by using a competition assay versus a direct binding assay. The latter gives no information on the binding constant, whereas a competition assay provides access to numerical binding constants. Thus, the present invention provides a test method which establishes common or similar structural motifs in IPGs and candidate IPG mimetic compounds, identifying mimetic compounds likely to have an IPG activity or activities in common or similar to the IPG. The compounds selected can then be subjected to further testing, providing lead compounds for further development as pharmaceuticals. In these aspects, where the candidate compounds are present in a library or mixture of compounds, the method may include the additional step of isolating compounds found to have the same or similar binding profiles to the IPG. This approach can help to increase the throughput of screening assay, allowing large numbers of candidate compounds to be screened. Alternatively or additionally, the binding profiles of more than one IPG can be determined and these profiles used to screen simultaneously for mimetics for these IPGs. Exemplary protocols for raising anti-IPG antibodies are set out below. Examples of antibodies that could be employed in the method include those produced by hybridoma cell lines 2F7, 2D1 and 5H6 deposited at European Collection of Cell Cultures (ECACC) under accession numbers 98051201, 98031212 and 98030901. Based on the teaching herein, the skilled person could readily prepare further antibodies having the same or different binding specificities for use in the present method. The inventors have surprisingly found that despite the fact that IPGs are small molecules and carbohydrates, it is possible to raise antibodies to them. Further, the fact that conjugation of the IPGs to a carrier is not required means that epitopes on the IPGs are not blocked or altered by the conjugation reaction, allowing antibodies to be raised to a full complement of epitopes on the IPGs. The method is applicable to the production of both polyclonal and monoclonal antibodies, as is demonstrated by the examples below. Preferably, the animal is immunised via an intraperitoneal route using a soluble form of the IPG. In a further aspect, the present invention provides a candidate mimetic compound as identifiable by the above methods . In a further aspect, the present invention provides an inositolphosphoglycan or candidate IPG mimetic compound binding profile as obtainable by the above methods. Conveniently, the antibodies are immobilised on a solid support so that they can be exposed to liquid samples containing the IPGs or candidate mimetics. Preferably, the different antibodies are immobilised at discrete locations on the support (e.g. individual wells on a multiwell plate or as microspots) so that they can be distinguished from each other. In a further aspect, the present invention provides a solid support having immobilised thereon a plurality of different anti-IPG antibodies, the individual antibodies being immobilised at discrete locations on the support. Preferably, the method employs at least 5 different anti- IPG antibodies, more preferably at least 10 antibodies, more preferably at least 15 antibodies and more preferably at least 20 antibodies. The use of larger numbers of antibodies that are specific for a range of epitopes of the IPG family members helps to ensure that the antibody binding profile obtained when the antibodies bind to the IPG family member can be distinguished from the profile obtained using other IPG family members. Embodiments of the present invention will now be described by way of example and not by limitation with reference to the accompanying drawings. Brief Description of the Drawings Figure 1 shows a dose-response curve of absorbance plotted against IPG concentration using anti-IPG antibodies in a Sandwich ELISA test. Figure 2 shows the results of experiments comparing the binding specificity of monoclonal antibody 5H6, a prior art polyclonal antibody raised against the GPI anchor of VSG and a polyclonal antibody raised against the cross reactive determinant (CRD) common to GPI anchored proteins. Figure 3 shows the results of a PDH phosphatase assay demonstrating that monoclonal antibody 5H6 is capable of inhibiting the action of P-type IPG from rat liver. Figure 4 shows binding profiles for 8 candidate compounds obtained using monoclonal antibody 2D1 as the binding agent and two polyclonal antibodies as developing agents. Figure 5 shows binding profiles for 8 candidate compounds obtained using monoclonal antibody 5H6 as the binding agent and two polyclonal antibodies as developing agents. Figure 6 shows binding profiles for 8 candidate compounds obtained using monoclonal antibody Al as the binding agent and two polyclonal antibodies as developing agents. Detailed Description IPGs and IPG Analogues Studies have shown that A-type mediators modulate the activity of a number of insulin-dependent enzymes such as CAMP dependent protein kinase (inhibits) , adenylate cyclase (inhibits) and cAMP phospho-diesterases (stimulates) . In contrast, P-type mediators modulate the activity of insulin-dependent enzymes such as pyruvate dehydrogenase phosphatase (stimulates) , glycogen synthase phosphatase (stimulates) and cAMP dependent protein kinase (inhibits) . The A- type mediators mimic the lipogenic activity of insulin on adipocytes, whereas the P-type mediators mimic the glycogenic activity of insulin on muscle. Both A and P-type mediators are mitogenic when added to fibroblasts in serum free media. The ability of the mediators to stimulate fibroblast proliferation is enhanced if the cells are transfected with the EGF-receptor. A-type mediators can stimulate cell proliferation in the CVG. Soluble IPG fractions having A-type and P-type activity have been obtained from a variety of animal tissues including rat tissues (liver, kidney, muscle brain, adipose, heart) and bovine liver. A and P-type IPG biological activity has also been detected in human liver and placenta, malaria parasitized RBC and mycobacteria. The ability of a polyclonal anti-inositolglycan antibody to inhibit insulin action on human placental cytotrophoblasts and BC3H1 myocytes or bovine-derived IPG action on rat diaphragm and chick cochleovestibular ganglia suggests cross -species conservation of many structural features. However, it is important to note that although some prior art references include reports of A and P-type IPG activity in some biological fractions, the purification or characterisation of the agents responsible for the activity was not disclosed until it was reported in the references below. A-type substances are cyclitol-containing carbohydrates, also containing Zn 2+ ion and optionally phosphate and having the properties of regulating lipogenic activity and inhibiting cAMP dependent protein kinase. They ma y also inhibit adenylate cyclase, be mitogenic when added to EGF-transfected fibroblasts in serum free medium, and stimulate lipogenesis in adipocytes. P-type substances are cyclitol-containing carbohydrates, also containing Mn 2+ and/or Zn 2+ ions and optionally phosphate and having the properties of regulating glycogen metabolism and activating pyruvate dehydrogenase phosphatase. They may also stimulate the activity of glycogen synthase phosphatase, be mitogenic when added to fibroblasts in serum free medium, and stimulate pyruvate dehydrogenase phosphatase. Methods for obtaining A-type and P-type IPGs are set out in detail in Caro et al, 1997 and in WO98/01116 and WO98/01117. Methods for obtaining the free GPI precursors of the A and P-type IPGs are set out below. Glycolipids were partially purified from rat liver membranes following the method described in Mato et al (1987) , with minor modifications (Varela-Nieto et al, 1993) . The membrane fraction was obtained by sequential centrifugation from 300 g of material. Total lipids were obtained by chloroform/methanol extraction followed by the removal of nonpolar lipids. GPI was separated from other phospholipids by sequential acid/base silica gel G60 t.l.c. (see below). Lipids were extracted from the t.l.c. plate with methanol, dried, applied to a Sep-Pak C18 cartridge, eluted with methanol, and dried. GPI was spotted onto the origin of a silica gel G60 t.l.c. plate which was developed twice in an acidic solvent system [chloroform: acetone:methanol: acetic acid:water (50:20:10:10:5, by volume)] and in a basic solvent system [chloroform:methanol: ammonium hydroxide:water (45:45:3:5:10, by volume)]. Alternatively, GPI molecules were further resolved by double-dimension t.l.c. as described in Clemente et al (1995) and Avila et al (1992) or by using high-performance (HP) -t.l.c. plates developed in chloroform:methanol:ammonium hydroxide:water (40:45:3:5:15, by volume) as described in Gaulton (1991). Lipid migration was calibrated in parallel with phospholipid standards that were detected by staining with iodine. In order to generate free IPGs from the purified GPI, the GPI was incubated with 1 unit of PI-PLC from Bacillus thuringiensis for 3 hours according to the manufacturer's instructions. At the end of the incubation, the reaction was terminated by loading the sample onto a Sep-Pak C18 cartridge. The water eluate (5ml) was dried. Antibodies Antibodies capable of specifically binding to P and A- type IPGs are disclosed herein and are used in assays involving IPGs and candidate mimetic compounds. These antibodies can be modified using techniques which are standard in the art. Antibodies similar to those exemplified for the first time here can also be produced using known methods. These methods of producing antibodies include immunising a mammal (e.g. mouse, rat, rabbit, horse, goat, sheep or monkey) with the IPG or a fragment thereof. Antibodies may be obtained from immunised animals using any of a variety of techniques known in the art, and screened, preferably using binding of antibody to antigen of interest. Isolation of antibodies and/or antibody-producing cells from an animal may be accompanied by a step of sacrificing the animal. As an alternative or supplement to immunising a mammal with an IPG, an antibody specific for an IPG may be obtained from a recombinantly produced library of expressed immunoglobulin variable domains, e.g. using lambda bacteriophage or filamentous bacteriophage which display functional immunoglobulin binding domains on their surfaces; for instance see WO92/01047. The library may be naive, that is constructed from sequences obtained from an organism which has not been immunised with any of the IPGs (or fragments) , or may be one constructed using sequences obtained from an organism which has been exposed to the antigen of interest. The term "monoclonal antibody" as used herein refers to an antibody obtained from a substantially homogenous population of antibodies, i.e. the individual antibodies comprising the population are identical apart from possible naturally occurring mutations that may be present in minor amounts . Monoclonal antibodies can be produced by the method first described by Kohler and Milstein, Nature, 256:495, 1975 or may be made by recombinant methods, see Cabilly et al, US Patent No. 4,816,567, or Mage and Lamoyi in Monoclonal Antibody Production Techniques and Applications, pages 79-97, Marcel Dekker Inc, New York, 1987. In the hybridoma method, a mouse or other appropriate host animal is immunised with the antigen by subcutaneous, intraperitoneal, or intramuscular routes to elicit lymphocytes that produce or are capable of producing antibodies that will specifically bind to the IPG used for immunisation. Alternatively, lymphocytes may be immunised in vitro. Lymphocytes then are fused with myeloma cells using a suitable fusing agent, such as polyethylene glycol, to form a hybridoma cell, see Goding, Monoclonal Antibodies: Principles and Practice, pp. 59-103 (Academic Press, 1986). Immunisation with soluble IPG and via the intraperitoneal route shown in the examples was surprisingly effective in producing antibodies specific for IPGs. The hybridoma cells thus prepared can be seeded and grown in a suitable culture medium that preferably contains one or more substances that inhibit the growth or survival of the unfused, parental myeloma cells. For example, if the parental myeloma cells lack the enzyme hypoxanthine guanine phosphoribosyl transferase (HGPRT or HPRT) , the culture medium for the hybridomas typically will include hypoxanthine, aminopterin, and thymidine (HAT medium) , which substances prevent the growth of HGPRT-deficient cells. Preferred myeloma cells are those that fuse efficiently, support stable high level expression of antibody by the selected antibody producing cells, and are sensitive to a medium such as HAT medium. Culture medium in which hybridoma cells are growing is assayed for production of monoclonal antibodies directed against the IPGs. Preferably, the binding specificity is determined by enzyme-linked immunoabsorbance assay (ELISA) . The monoclonal antibodies of the invention are those that specifically bind to either or both P and A- type IPGs. The epitope bound by the antibodies can be mapped using synthetic compounds known to bind to one of the deposited antibodies, e.g. to see whether an antibody has substantially the same or the same binding specificity as the deposited monoclonal antibodies 2F7, 2D1 or 5H6. This can also be carried out in competitive studies to determine whether a given anti-IPG antibody competes with one of the deposited antibodies for a particular IPG epitope. Thus, the present invention includes antibodies which are capable of binding to an IPG epitope bound by an exemplified antibody. Preferably, this epitope is present on both rat liver A-type IPG and human placenta P-type IPG. The exemplified monoclonal raised using rat liver A-type IPGs are surprisingly effective in assays for the diagnosis of pre-eclampsia, as shown in the examples below. In a preferred embodiment of the invention, the monoclonal antibody will have an affinity which is greater than micromolar or greater affinity as determined (i.e > 10 6 mol) , for example, by Scatchard analysis, see Munson & Pollard, Anal. Biochem. , 107:220, 1980. After hybridoma cells are identified that produce neutralising antibodies of the desired specificity and affinity, the clones can be subcloned by limiting dilution procedures and grown by standard methods. Suitable culture media for this purpose include Dulbecco's Modified Eagle's Medium or RPM1-1640 medium. In addition, the hybridoma cells may be grown in vivo as ascites tumours in an animal. The monoclonal antibodies secreted by the subclones are suitably separated from the culture medium, ascites fluid, or serum by conventional immunoglobulin purification procedures such as, for example, protein A- Sepharose, hydroxylapatite chromatography, gel electrophoresis, dialysis, or affinity chromatography. Nucleic acid encoding the monoclonal antibodies of the invention is readily isolated and sequenced using procedures well known in the art, e.g. by using oligonucleotide probes that are capable of binding specifically to genes encoding the heavy and light chains of murine antibodies . The hybridoma cells of the invention are a preferred source of nucleic acid encoding the antibodies or fragments thereof. Once isolated, the nucleic acid is ligated into expression or cloning vectors, which are then transfected into host cells, which can be cultured so that the monoclonal antibodies are produced in the recombinant host cell culture. Hybridomas capable of producing antibody with desired binding characteristics are within the scope of the present invention, as are host cells containing nucleic acid encoding antibodies (including antibody fragments) and capable of their expression. The invention also provides methods of production of the antibodies including growing a cell capable of producing the antibody under conditions in which the antibody is produced, and preferably secreted. Antibodies according to the present invention may be modified in a number of ways. Indeed the term "antibody" should be construed as covering any binding substance having a binding domain with the required specificity. Thus, the invention covers antibody fragments, derivatives, functional equivalents and homologues of antibodies, including synthetic molecules and molecules whose shape mimics that of an antibody enabling it to bind an antigen or epitope, here a P or A-type inositolphosphoglycan. Examples of antibody fragments, capable of binding an antigen or other binding partner, are the Fab fragment consisting of the VL, VH, Cl and CHI domains; the Fd fragment consisting of the VH and CHI domains; the Fv fragment consisting of the VL and VH domains of a single arm of an antibody; the dAb fragment which consists of a VH domain; isolated CDR regions and F(ab') 2 fragments, a bivalent fragment including two Fab fragments linked by a disulphide bridge at the hinge region. Single chain Fv fragments are also included. A hybridoma producing a monoclonal antibody according to the present invention may be subject to genetic mutation or other changes. It will further be understood by those skilled in the art that a monoclonal antibody can be subjected to the techniques of recombinant DNA technology to produce other antibodies, humanised antibodies or chimeric molecules which retain the specificity of the original antibody. Such techniques may involve introducing DNA encoding the immunoglobulin variable region, or the complementarity determining regions (CDRs) , of an antibody to the constant regions, or constant regions plus framework regions, of a different immunoglobulin. See, for instance, EP-A-184187, GB-A- 2188638 or EP-A-0239400. Cloning and expression of chimeric antibodies are described in EP-A- 0120694 and EP- A-0125023. Immunoassays The antibodies described above can be employed in the method aspects of the invention in a wide variety of different assay formats. The antibodies can be used as binding agents capable of specifically binding to P and/or A-type IPGs or as developing agents for determining the fraction of binding sites of a binding agent occupied by analyte after exposure to a test sample. In some instances, employing the antibodies, particularly as developing agents in assays, involves tagging them with a label or reporter molecule which can directly or indirectly generate detectable, and preferably measurable, signals. The linkage of reporter molecules may be directly or indirectly, covalently, e.g. via a peptide bond or non-covalently. Linkage via a peptide bond may be as a result of recombinant expression of a gene fusion encoding antibody and reporter molecule. Any method known in the art for separately conjugating the antibody to the detectable moiety may be employed, including those methods described by Hunter et al, Nature 144:945, 1962; David et al, Biochemistry 13:1014, 1974; Pain et al, J. Immunol. Meth. 40:219, 1981; and Nygren, J Histoche . and Cytochem. 30:407, 1982. One favoured mode is by covalent linkage of each antibody with an individual fluorochrome, phosphor or laser dye with spectrally isolated absorption or emission characteristics. Suitable fluorochromes include fluorescein, rhodamine, luciferin, phycoerythrin and Texas Red. Suitable chromogenic dyes include diaminobenzidine. Other detectable labels include radioactive isotopic labels, such as 3 H, 14 C, 3 P, 35 S, 16 I, or 9m Tc, and enzyme labels such as alkaline phosphatase, β-galactosidase or horseradish peroxidase, which catalyze reactions leading to detectable reaction products and can provide amplification of signal. Other reporters include macromolecular colloidal particles or particulate material such as latex beads that are coloured, magnetic or paramagnetic, and biologically or chemically active agents that can directly or indirectly cause detectable signals to be visually observed, electronically detected or otherwise recorded. These molecules may be enzymes which catalyze reactions that develop or change colours or cause changes in electrical properties, for example. They may be molecularly excitable, such that electronic transitions between energy states result in characteristic spectral absorptions or emissions. They may include chemical entities used in conjunction with biosensors. Alternatively or additionally, the antibodies can be employed as binding agents, relying on the fact that the antibodies are capable of specifically binding the IPGs in preference to other substances present in the sample. Conveniently, the binding agent (s) are immobilised on solid support, e.g. at defined locations, to make them easy to manipulate during the assay. This can be achieved using techniques well known in the art such as physisorption or chemisorption, e.g. employing biotin/avidin or biotin/streptavidin to chemically link the antibodies to the solid support. Generally, the sample is contacted with the binding agent (s) under appropriate conditions so that P and A-type IPGs present in the sample can bind to the binding agent (s). The fractional occupancy of the binding sites of the binding agent (s) can then be determined using a developing agent or agents. As mentioned above, the developing agents are labelled (e.g. with radioactive, fluorescent or enzyme labels) so that they can be detected using techniques well known in the art. Thus, radioactive labels can be detected using a scintillation counter or other radiation counting device, fluorescent labels using a laser and confocal microscope, and enzyme labels by the action of an enzyme label on a substrate, typically to produce a colour change. The developing agent (s) can be used in a competitive method in which the developing agent competes with the analyte for occupied binding sites of the binding agent, or non-competitive method, in which the labelled developing agent binds analyte bound by the binding agent or to occupied binding sites. Both methods provide an indication of the fraction of the binding sites occupied by the analyte, and hence the concentration of the analyte in the sample, e.g. by comparison with standards obtained using samples containing known concentrations of the analyte. The antibodies of the present invention may be employed in any known assay method, such as competitive binding assays, direct and indirect sandwich assays, and immunoprecipitation assays, see Zola, Monoclonal Antibodies: A Manual of Techniques, pp 147-158 (CRC Press, Inc, 1987) . Sandwich assays involve the use of two antibodies, each capable of binding to a different immunogenic portion, or epitope, of the IPG to be detected, in a sandwich assay, the test sample analyte is bound by a first antibody which is immobilised on a solid support, and thereafter a second antibody binds to the analyte, thus forming an insoluble three part complex. The second antibody may itself be labelled with a detectable moiety (direct sandwich assays) or may be measured using an anti- immunoglobulin antibody that is labelled with a detectable moiety (indirect sandwich assay) . For example, one type of sandwich assay is an ELISA assay, in which case the detectable moiety is an enzyme. There is also an increasing tendency in the diagnostic field towards miniaturisation of such, e.g. making use of binding agents, such as antibodies immobilised in small, discrete locations (microspots) and/or as arrays on solid supports or on diagnostic chips. In one embodiment, the present invention provides a support having immobilised at discrete locations thereon a plurality of anti-IPG antibodies . These approaches can be particularly valuable as they can provide great sensitivity (particularly through the use of fluorescent labelled reagents) , require only very small amounts of the candidate compounds or IPGs being tested and allow a variety of separate assays can be carried out simultaneously. This latter advantage can be useful in screening libraries of compounds produced by combinantorial techniques. Examples of techniques enabling this miniaturised technology are provided in WO84/01031, WO88/1058, WO89/01157, W093/8472, W095/18376/ W095/18377, W095/24649 and EP-A-0373203. Affinity Purification The antibodies of the invention also are useful as affinity purification agents. In this process, the antibodies capable of specifically binding P- and/or A- type IPGs are immobilized on a suitable support, such as Sephadex ® resin or filter paper, using methods well known in the art. The immobilized antibody then is contacted with a sample containing the IPGs to be purified, and thereafter the support is washed with a suitable solvent that will remove substantially all the material in the sample except the IPGs, which is bound to the immobilised antibody. Finally, the support is washed with another suitable solvent, such as glycine buffer, pH 3-5, that will release the IPGs from the antibody. Mimetic Design The designing of mimetics to a known pharmaceutically active compound is a known approach to the development of pharmaceuticals based on a "lead" compound. This might be desirable where the active compound is difficult or expensive to synthesise or where it is unsuitable for a particular method of administration, e.g. peptides are unsuitable active agents for oral compositions as they tend to be quickly degraded by proteases in the alimentary canal. Mimetic design, synthesis and testing is generally used to avoid randomly screening large number of molecules for a target property. There are several steps commonly taken in the design of a mimetic from a compound having a given target property. Firstly, the particular parts of the compound that are critical and/or important in determining the target property are determined. These parts of the compound constituting its active region are known as its "pharmacophore" . Once the pharmacophore has been found, its structure is modelled to according its physical properties, e.g. stereochemistry, bonding, size and/or charge, using data from a range of sources, eg spectroscopic techniques, X- ray diffraction data and NMR. Computational analysis, similarity mapping (which models the charge and/or volume of a pharmacophore, rather than the bonding between atoms) and other techniques can be used in this modelling process. In a variant of this approach, the three- dimensional structure of the ligand and its binding partner are modelled. This can be especially useful where the ligand and/or binding partner change conformation on binding, allowing the model to take account of this the design of the mimetic. A template molecule is then selected onto which chemical groups which mimic the pharmacophore can be grafted. The template molecule and the chemical groups grafted on to it can conveniently be selected so that the mimetic is easy to synthesise, is likely to be pharmacologically acceptable, and does not degrade in vivo, while retaining the biological activity of the lead compound. The mimetic or mimetics found by this approach can then be screened to see whether they have the target property, or to what extent they exhibit it. Further optimisation or modification can then be carried out to arrive at one or more final mimetics for in vivo or clinical testing. Example 1 Production of Polyclonal and Monoclonal Antibodies Against Inositolphosphoglycans (IPGs) Inositolphosphoglycan (soluble form) obtained by PI-PLC treatment of GPI purified from rat liver by sequential Thin Layer Chromatography (TLC) was used to immunize New Zealand rabbits and Balb/c mice as described below. Alternatively, human IPGs could be obtained using the methods described in Caro et al, 1997. Rabbit Immunisation Procedure Two New Zealand rabbits were anaesthetized and then immunised with 750μg of IPG (soluble form) mixed in 1ml of PBS with 1ml of complete Freund's adjuvant (CFA) . The antigen-adjuvant emulsion was administered 1.5ml by intradermal (id) injection and 0.5ml by intramuscular (im) injection. After one month, this protocol was repeated except that incomplete Freund's adjuvant (IFA) was used, and 1.5ml by administered by subcutaneous (sc) injection and 0.5ml by intramuscular (im) injection. This was repeated again on days 60, 90, 120 and 150. Mouse Immunisation Procedure Four female Balb/c 6 weeks old mice were immunised with 60μg of IPG (soluble form) in 250μl of PBS with 250μl of CFA. The antigen-adjuvant emulsion was injected by intraperitoneal (ip) injection. After 21 days, the injection was repeated except that IFA was used. On days 42 and 63 all the animals were injected ip with IFA. On day 84, the best responder was injected lOOμl PBS containing 60μg of IPG intravenous (iv) and lOOμl PBS containing 60μg of IPG (ip) . After 87 days, splenocytes from best responder were fused to yleoma cells using conventional techniques. Monitor test bleeds were realized regularly. Example 2 indirect ELISA Assay The following indirect ELISA protocol is provides as an example of a procedure for screening for the monoclonal antibodies. Add lOOμl/well in all the steps. (1) Add IPG diluted 1:800 in PBS in a F96 Polysorp Nunc- Immuno plate. Incubate at least 7 days at 4°C. (2) Wash with PBS three times. (3) Add a blocking reagent for ELISA (Boehringer Mannheim) in distilled water (1:10 v/v) for 2 hours at room temperature. (4) Wash with PBS-Tween 20 (0.1%) three times. (5) Add a purified monoclonal and/or a polyclonal antibody (diluted between 1:12.5 and 1:3200 in PBS), overnight at 4°C. (6) Wash with PBS-Tween 20 (0.1%) three times. (7) Add an anti -mouse IgM, biotinylated whole antibody (from goat) (Amersham) in case of the previous addition of a monoclonal antibody, or add an anti -rabbit Ig, biotinylated species -specific whole antibody (from donkey) (Amersham) , in case of previous addition of a polyclonal antibody, both of them diluted 1:1000 in PBS, 1 h 30 min at room temperature. (8) Wash with PBS-Tween 20 (0.1%) three times. (9) Add a streptavidin-biotinylated horseradish peroxidase complex (Amersham) diluted 1:500 in PBS, 1 h 30 min at room temperature. (10) Wash with PBS three times. (11) Add 2,2-Azino-di- (3 -ethylbenzthiazoline sulfonate (6)) diammonium salt crystals (ABTS) to buffer for ABTS (Boehringer Mannheim) : Buffer for ABTS is added to distilled water (1:10 v/v). Img of ABTS is added to 1ml of diluted buffer for ABTS. (12) Read the absorbance in a Multiskan Plus P 2.01 using a 405 nm filter in 5-15 min. Comments : Solvents used are phosphate-buffered saline (PBS) pH 7.2 or PBS-Tween 20 (0.1%). Step 1: IPG (soluble form) is used in an indirect ELISA (initial concentration approximately 60μM) . Working dilutions are normally between 1:400 and 1:800. Several incubation times have been examined. The best and more reproducible results have been obtained when incubation time is at least seven days at 4°C, probably because higher incubation times increase the number of molecules of IPG that are bound to the solid phase. Step 3: Blocking reagent for ELISA is a registered product of Boehringer Mannheim. In order to prepare the solution we must dissolve the content (27g) in 100 ml redist. Water at room temperature while stirring for approx 30 minutes. The concentrate is stable when stored in aliquots at -20°C. For use, dilute one aliquot in a ratio of 1:10 with redistilled water to yield a working solution containing 1% protein mixture (w/v) that was obtained by proteolytic degradation of purified gelatin, in 50mM Tris-HCl, 150mM NaCl, pH ca.7.4. Step 5: A purified monoclonal and/or polyclonal antibody are used in an indirect ELISA (initial concentration approx 2mg/ml) . Working dilutions are normally between 1:100 and 1:200, getting final concentrations of 20μg/ml and lOμg/ml respectively) . Incubation time for rapid assays can be two hours at room temperature. Step 7: The anti -rabbit and the anti -mouse antibodies are used at 1:1000 dilution straight from the stock bottle. The stock bottle is stored at 2-8°C. Under these conditions the product is stable for at least six months, after which any remaining solution is discarded. 1ml of biotinylated reagent is supplied in 0.1 M phosphate- buffered saline of pH7.5 containing 1% (w/v) bovine serum albumin and 0.05% (w/v) sodium azide. Step 9: Streptavidin-biotinylated/HRP is used at 1:500 dilution straight from the stock bottle. The stock bottle is stored at 2-8°C. Under these conditions the product is stable for at least three months, after which any remaining solution is discarded. The complex is supplied in 2ml of phosphate-buffered saline pH7.5 containing 1% (w/v) bovine serum albumin and an antimicrobial agent. Step 11: ABTS buffer is a registered product of Boehringer Mannheim. The solution consists of sodium perborate, citric acid and disodium hydrogen phosphate. The solution is stored in aliquots of 1ml at -20°C. For use, dilute one aliquot in a ratio of 1:10 with redistilled water. Example 3 Sandwich ELISA Assay The following ELISA protocol is provided as an example of an assay for IPGs employing the deposited monoclonal antibodies . Add 100 μl/well in all the steps. (1) Anti-IPG monoclonal antibody was diluted 1:100 in PBS in added to a F96 Maxisorp Nunc-Immuno plate. The plate was incubated for at least 2 days at 4°C. (2) The plate was washed with PBS three times. (3) Blocking reagent for Elisa (Boehringer Mannheim) in distilled water (1.5:10 v/v) was added for 2 hours at room temperature. (4) The plate was washed with PBS-Tween 20 (0.1%) three times. (5) Human serum diluted 1:4 in PBS was added to the plate overnight at 4°C. (6) The plate was wash with PBS-Tween 20 (0.1%) three times. (7) A purified polyclonal antibody (diluted 1:100 in PBS) was added overnight at 4 C C. (8) The plate was washed with PBS-Tween 20 (0.1%) three times . (9) An anti-rabbit Ig, biotinylated species -specific whole antibody (from donkey ) (Amersham) was diluted 1:1000 in PBS, and added to the plate for 1 h 30 min at room temperature. (10) Wash with PBS-Tween 20 (0.1%) three times. (11) Add a streptavidin-biotinylated horseradish peroxidase complex (Amersham) diluted 1:500 in PBS, 1 h 30 mins at room temperature. (12) The plate was washed with PBS three times. (13) 2,2 ' -Azino-di- (3 -ethylbenzthiazoline sulfonate (6)) diammonium salt crystals (ABTS) was made up in buffer for ABTS (Boehringer Mannheim) . The buffer for ABTS was added to distilled water (1:10 v/v). lmg of ABTS was added to 1ml of diluted buffer for ABTS. (14) The absorbance was read in a Multiskan Plus P 2.01 using a 405 nm filter in 15-30 mins. Comments : The solvents used were phosphate-buffered saline (PBS) pH7.2 or PBS-Tween 20 (0.1%). In step (1) : The examples employed purified monoclonal antibody 2D1 in the Sandwich ELISA assays (initial concentration 2.5mg/ml). Working dilutions varied normally between 1:100 and 1:200, with final concentrations of 25μg/ml and 12.5μg/ml, respectively. The incubation time used in the assay can be varied. For rapid assays, incubation time can vary between two hours at room temperature or overnight at 4 C C. However, improved results are obtained when incubation time is at least two days at 4°C. This improvement may be due to the higher incubation times increasing the number of molecules of monoclonal antibody that are bound to the solid phase. Step (3) : Blocking reagent for ELISA is a registered product of Boehringer Mannheim. In order to prepare the solution, the content (27g) was dissolved in 100ml redistilled water at room temperature while stirring for approximately 30mins. The concentrate is stable when stored in aliquots at -20°C. For use, aliquots were diluted in a ratio of 1:10 with redistilled water to yield a working solution containing 1% protein mixture (w/v) that was obtained by proteolytic degradation of purified gelatin, in 50 mM Tris-HCl, 150 mm NaCl, pH ca. 7.4. Step (5) : Human serum was probed in several dilutions (1:1, 1:2, 1:4...). Working dilutions are normally between 1:2 and 1:4. IPG in several dilutions was used as a standard (positive control) . Wells without serum are used as negative control. The incubation time for rapid assays was two hours at room temperature. Step (7) : A purified polyclonal antibody was used in Sandwich ELISA (initial concentration 2 mg/ml) . Working dilutions were between 1:100 and 1:200, with final concentrations of 20μg/ml and lOμg/ml respectively. Step (9): The anti-rabbit was used at 1:1000 dilution straight from the stock bottle, stored at 28°C. Under these conditions the product is stable for at least six months. 1ml of biotinylated reagent is supplied in 0.1 M phosphate-buffered saline pH 7.5 containing 1% (w/v) bovine serum albumin and 0.05% (w/v) sodium azide. Step (11) : Streptavidin-biotinylated/HRP was used at 1:500 dilution straight from the stock bottle, stored at 2-8°C. Under these conditions the product is stable for at least three months. The complex is supplied in 2ml of phosphate-buffered saline pH 7.5 containing 1% (w/v) bovine serum albumin and an antimicrobial agent. Step (13) : ABTS buffer is a registered product of Boehringer Mannheim. The solution consists of sodium perborate, citric acid and disodium hydrogen phosphate. The solution is stored in aliquots of 1ml at -20°C. For use, one aliquot is diluted in a ratio of 1:10 with redistilled water. Figure 1 shows a dose-response curve of assay response (absorbance) plotted against IPG concentration, demonstrating that the antibodies can be used to assay for IPGs. Example 4 Properties of Anti-IPG Antibody 5H6 As discussed above, a prior art polyclonal antibody raised against the GPI -anchor of VSG was found to cross - react with IPG containing fractions. Figure 2 shows that a polyclonal antibody raised against IPGs cross reacted with GPI -anchors. Thus, these results are consistent and demonstrate that there is some cross reactivity between the IPG and GPI anchors. In contrast, when the reactivity of monoclonal antibody 5H6 towards soluble and membrane bound VSG was tested, figure 2 (left hand column) shows that it does not cross react in the same way as the polyclonal antibody raised against IPGs (middle column) . In these experiments, a polyclonal antibody raised against the common reactive determinant (CRD) common to GPI anchored proteins was used as a positive control (right hand column) . Thus, figure 2 shows that antibody 5H6 does not cross react with either soluble or membrane bound VSG, whereas both polyclonal antibodies react strongly. This property distinguishes the antibodies of the invention from cross reacting polyclonal antibodies. This in turn suggests that polyclonal antibodies will not specifically detect IPGs, but are a valuable reagent in ELISA sandwich assays which require two anti-IPG antibodies, one of which is very specific (monoclonal) and the other of general reactivity (polyclonal) . Figure 3 shows that monoclonal antibody 5H6 is capable of inhibiting the action of P-type IPG from rat liver in a P-type phosphatase assay. Thus, this and similar antibodies could be used as P-type IPG antagonists, e.g. in the treatment of conditions associated with elevated levels of P-type IPGs such as pre-eclampsia. Example 5 Use of Anti-IPG Antibodies to Screen for IPG Mimetics By way of example, the following approach could be used to screen for mimetics for a given IPG. Firstly, a group of antibodies having different IPG binding activities are used to provide binding profiles for a given IPG, e.g. P-type IPG isolated from human placenta, or P or A-type IPGs isolated from human liver. Ideally, the number of antibodies used should be sufficient to provide a unique binding profile, or the conditions under which the binding profile is obtained adjusted to assist in this aim. These results could be used to define a table of binding profiles. Table 1: Antibody P-type IPG A-type IPG P-type IPG Placenta Liver Liver O 99/47926 36 Ab, Yes Yes Yes Ab, NO No Yes Ab n Yes No No The table could record simply whether the antibodies bound a given IPG, i.e. the epitope that the antibody was specific for was present on the IPG, or whether the binding was above a particular threshold level or whether record the actual strength of the interaction between the antibody and the IPG. Given the application of the invention in screening large numbers of candidate mimetics, it is desirable that the determination of binding is as simple as possible. Once the binding profile for a given IPG has been found, the exercise could be repeated, to screen a library of candidate compounds using the antibodies to determine their binding profiles. A comparison of the binding profiles of the IPGs and the candidate compounds would then indicate candidate compounds likely to resemble the given IPG, that consequently are likely to be useful leads for pharmaceuticals. Example 6 Assay Using Monoclonal Antibodies 2D1, 5H6 and Al to Obtain IPG Binding Profiles An ELISA assay using monoclonal antibody 2D1 as a binding agent and a labelled polyclonal developing antibodies raised against rat liver A-type IPG and human placental P-type IPG was used to establish binding profiles for a series of synthetic compounds SNKll, SNK8 , SNK7, SNK6 , SNK12, SNK13, C4 and C3. Compound C3, ID-6-0- (2 -amino-2 - deoxy-α-D-glucopyranosyl) -myo-inositol 1,2- (cyclic phosphate) , has been prepared previously, see Zapata et al, 1994. Compound C4 , 1D-6-0- (2-amino-2 -deoxy-α-D- glucopyranosyl) -chiro-inositol 1 -phosphate can be synthesised as described in Jaramillo et al, 1994. Figure 4 shows that candidate synthetic compounds C3, C4 and SNK12 showed appreciable binding to monoclonal 2D1 and the polyclonal developing agent raised against rat liver A-type IPG. Figure 5 shows a similar assay using monoclonal antibody 5H6, showing appreciable responses using the rat liver A- type IPG and candidate compounds SNK6, SNK12, SNK13 and C4. This assay also shows that weaker responses were obtained using the placenta P-type developing agent with compounds SNK6 and C4. Figure 6 shows a further assay using anti-IPG monoclonal antibody Al. This antibody reacted positively with all of the candidate compounds using the rat liver A-type IPG developing antibody, but illustrates that a binding profile distinguishing candidate compounds or IPGs could be based on the magnitude of the binding response as an alternative or in addition to an assay for determining whether or not binding takes place. Similar profiles have been obtained using natural IPGs (data not shown) . The comparison of the profiles obtained for the candidate mimetics and the IPGs can therefore be used to select mimetics likely to share an IPG biological activity for further testing. Thus, the assays illustrate that the binding profiles provided by the present invention are dependent on the binding agents and developing agents used, as well as the identity of the IPGs or synthetic compounds. Further, the profile can include either or both the existence of a positive or negative response or the magnitude of it. Table 2 collates the data from the assays using the rat liver A-type developing agent to demonstrate that just 3 assays provides enough information to distinguish the binding of 8 candidate compounds. Positive responses are rated out of 5. Table 2: Compound/Ab 2D1 5H6 Al SNK11 1/5 1/5 2/5 SNK8 - 1/5 1/5 SNK7 - - 5/5 SNK6 - 2/5 5/5 SNK12 1/5 1/5 3/5 SNK13 - 2/5 3/5 C4 2/5 3/5 2/5 C3 4/5 - 1/5 Taken together, these assays demonstrate that it is possible to define a binding profile using different anti-IPG antibodies as capture and developing agents for candidate compounds or a given IPG. The assays could be repeated with further anti-IPG antibodies as binding and developing agents, to develop more precise binding profiles for different type of IPGs and candidate synthetic compounds. Deposits The deposit of hybridomas 2F7, 2D1 and 5H6 in support of this application was made at the European Collection of Cell Cultures (ECACC) under the Budapest Treaty by Rademacher Group Limited (RGL) , The Windeyer Building, 46 Cleveland Street, London W1P 6DB, UK. The deposits have been accorded accession numbers accession numbers 98051201, 98031212 and 98030901. RGL give their unreserved and irrevocable consent to the materials being made available to the public in accordance with appropriate national laws governing the deposit of these materials, such as Rules 28 and 28a EPC. The expert solution under Rule 28(4) EPC is also hereby requested. 99/47926 40 References : The reference mentioned herein are all incorporated by reference in their entirety. WO98/01116 and W098/01117 (Rademacher Group Limited) . Caro et al, Biochem. Molec. Med. , 61:214-228, 1997. Kunjara et al, In: Biopolymers and Bioproducts: Structure, Function and Applications, Ed Svati et al, 301-305, 1995. Rademacher et al, Brazilian J. Med. Biol. Res., 27:327- 341, 1994. Nestler et al, Endocrinology, 129:2951-2956, 1991. Romero et al, P.N.A.S., 87:1476-1480, 1990. Huang et al, Endocrinology, 132:652-657, 1993. Represa et al, P.N.A.S., 88:8016-8019, 1991. Mato et al, J. Biol. Chem. , 262:2131-2137, 1987 Clemente et al, Cell Signalling, 7:411-421, 1991. Varela-Nieto et al, In Handbook of Endocrine Research Techniques : intracellular Mediators of Peptide Hormone Action: Glycosylphospatidylinositol/lnositol Phosphoglycan System, ed de Pablo et al, San Diego: Academic Press, 391-406, 1993. Avila et al, Biochem. J. , 282:681-686, 1992. Gaulton, Diabetes, 40:1297-1304, 1991. Zapata et al, Carbohydrate Res., 264;21-31, 1994. Jaramillo et al, J. Org. Chem, 59:3135-3141, 1994.

Claims: Claims : 1. A method for determining a binding profile for an inositolphosphoglycan (IPG) or a candidate mimetic compound, the method comprising contacting the IPG or candidate mimetic compound with an anti-IPG antibody in a binding assay and determining the binding of the IPG or candidate mimetic compound to the antibody to provide the binding profile. 2. The method of claim 1 wherein the binding profile comprises the results of binding assays in which more than one IPG or candidate mimetic compound is contacted with a given anti-IPG antibody. 3. The method of claim 1 or claim 2 wherein the binding profile comprises the results of binding assays in which more than one anti-IPG antibody is contacted with the IPGs or candidate mimetic compounds. 4. A method for identifying inositolphosphoglycan (IPG) mimetics, the method comprising: (a) contacting a P or A-type IPG with an anti-IPG antibody in a binding assay and determining the binding of the IPG to the antibody to provide a binding profile for the IPG; (b) contacting one or more candidate mimetic compounds with the anti-IPG antibody in a binding assay and determining the binding of the candidate mimetic compounds to the antibody to provide binding profiles for the candidate mimetic compounds; and, (c) comparing the binding profiles of the IPG and candidate mimetic compounds to identify for candidate mimetic compounds likely to have the IPG activity. 5. A method for screening for inositolphosphoglycan (IPG) mimetics, the method comprising having contacted a P or A-type IPG with an anti-IPG antibody in a binding assay to determine a binding profile for the IPG, the further steps of: (a) contacting one or more candidate mimetic compounds with the anti-IPG antibody in a binding assay and determining the binding of the candidate mimetic compounds to the antibody to provide the binding profiles for the candidate mimetic compounds; and, (b) comparing the binding profiles of the IPG and candidate mimetic compounds to identify candidate mimetic compounds likely to have given IPG activity. 6. The method of claim 4 or claim 5 further comprising the step of testing a candidate mimetic compound identified in the method to determine whether it has a desired IPG activity. 7. The method of any one of claims 4 to 6 wherein the binding profile comprises the results of binding assays in which more than one IPG or candidate mimetic compound is contacted with a given anti-IPG antibody. 8. The method of any one of claims 4 to 7 wherein the binding profile comprises the results of binding assays in which more than one anti-IPG antibody is contacted with the IPGs or candidate mimetic compounds. 9. The method of any one of the preceding claims wherein the anti-IPG antibodies are immobilised on a solid support. 10. The method of claim 9 wherein at least 5 different anti-IPG antibodies are immobilised on the solid support. 11. The method of claim 9 or claim 10 wherein at least 10 different anti-IPG antibodies are immobilised on the solid support. 12. The method of any one of claim 9 to 11 wherein the anti-IPG antibodies are immobilised at discrete locations on the support 13. The method of claim 12 wherein the support is a silicon chip or polystyrene plate. 14. The method of any one of the preceding claims wherein the anti-IPG antibody is produced by hybridoma cell lines 2F7, 2D1 or 5H6 deposited at European Collection of Cell Cultures (ECACC) under accession numbers 98051201, 98031212 and 98030901. 15. The method of any one of the preceding claims wherein the binding profile expresses a positive or negative response in the binding assay between the IPG or candidate mimetic compound and the anti-IPG antibody. 16. The method of any one of claims 1 to 14 wherein the binding profile expresses the magnitude of binding response of the IPG or candidate mimetic compound for a given antibody 17. The method of any one of the preceding claims wherein the binding response in the assay is measured using a labelled competitive or noncompetitive developing agent. 18. The method of claim 17 wherein the developing agent is labelled anti-IPG antibody. 19. The method of claim 17 or claim 18 wherein the developing agent is polyclonal antisera. 20. The method of any one of claims 4 to 19 wherein a library of candidate mimetic compounds are screened together. 21. The method of claim 20 which comprises the additional step of isolating a candidate mimetic compounds from a library of compounds identified in the method to have a binding profiles which is the same or similar to the binding profile of the IPG. 22. The method of claim 21 wherein the candidate mimetic compound is isolated by affinity chromatography using an anti-IPG antibody. 23. A candidate mimetic compound as identifiable by the method of any one of claims 4 to 21. 24. An inositolphosphoglycan or candidate IPG mimetic compound binding profile as obtainable by the method of any one of claims 1 to 3. 25. A solid support for determining binding profiles of inositolphosphoglycans or candidate mimetic compounds, the solid support having immobilised thereon a plurality of different anti-IPG antibodies at discrete locations on the support . 26. The solid support of claim 25 having at least 5 different anti-IPG antibodies are immobilised thereon. 27. The solid support of claim 25 or claim 26 having at least 10 different anti-IPG antibodies are immobilised thereon.

Inventors: RADEMACHER THOMAS WILLIAM, WILLIAMS PHILLIP, RADEMACHER, THOMAS, WILLIAM, WILLIAMS, PHILLIP
Applicants: RADEMACHER GROUP LIMITED, RADEMACHER THOMAS WILLIAM, WILLIAMS PHILLIP, RADEMACHER, THOMAS, WILLIAM, WILLIAMS, PHILLIP
Application year: 1999
Main classification: G01N33
IPC codes: G01N33