The present invention relates to antibodies to novel members of the Tumor Necrosis Factor (TNF) receptor family called TR2 receptor and their uses in pathological conditions. Hybridoma cell lines producing such mAbs, methods of in vivo imaging of pathological conditions, and methods of treating and diagnosing pathological conditions, caused by abnormal functioning, production or metabolism of TR2 receptors are also provided. In vitro assays for detecting the presence of TR2 and for evaluating the binding affinity of a test compound are also described.

EXAMPLES The examples below are carried out using standard techniques, which are well known and routine to those of skill in the art, except where otherwise described in detail. The examples illustrate, but do not limit the invention. 
 Generation of TR2-Ig 
 Expression and Purification of TR2-Fc(TR2-Ig Fusion Protein) and Cleaved TR2 The putative transmembrane domain of translated TR2 receptor was determined by hydrophobicity using the method of Goldman et al. (Ann. Rev. of Biophys. Biophys. Chem. 15:321-353 (1986)) for identifying nonpolar transbilayer helices. The region upstream of this transmembrane domain, encoding the putative leader peptide and extracellular domain, was chosen for the production of an Fc fusion protein. Primers were designed to PCR the corresponding coding region from HTXBS40 (a clone containing TR2 receptor clone) with the addition of a BglII site (single underlined), a Factor Xa protease site and an Asp718I site (double underlined) at the 3 end. PCR with this primer pair (forward 35-mer: 5′ CAGGAATTCGCAGCCATGGAGCCTCCTGGAGACTG 3′ (SEQ ID NO:3), and reverse primer 53-mer: 5′ CCATACCCA GGTACC CCTTCCCTCGAT AGATCT TGCCTTCGTCACCAGCCAGC 3′ (SEQ ID NO:4)), which contains 18 nucleotides of the TR2 coding sequence, resulted in one band of the expected size. This was cloned into COSFclink to give the TR2-Fclink plasmid. The PCR product was digested with EcoRI and Asp718I and ligated into the COSFclink plasmid (Johansen, et al., J. Biol. Chem. 270:9459-9471 (1995)) to produce TR2-Fclink. COS cells were transiently transfected with TR2-Fclink and the resulting supernatant was immunoprecipitated with protein A agarose. Western blot analysis of the immunoprecipitate using goat anti-human Fc antibodies revealed a strong band consistent with the expected size for glycosylated TR2-Fc (greater than 47.5 kD). A 15 L transient COS transfection was performed and the resulting supernatant was purified (see below). The purified protein was used to immunize mice following DNA injection for the production of mAbs. CHO cells were transfected with TR2-Fclink to produce stable cell lines. Five lines were chosen by dot blot analysis for expansion and were adapted to shaker flasks. The line with the highest level of TR2-Fc protein expression was identified by Western blot analysis. TR2-Fc protein purified from the supernatant of this line was used for cell binding studies by flow cytometry, either as intact protein or after factor Xa cleavage and biotinylation. Clone HTXBS40 is an allelic variant of TR2 which differs from the sequence shown in SEQ ID NO: 1 in that HTXBS40 contains guanine at nucleotide 314, thymine at nucleotide 386 and cytosine at nucleotide 627. A plasmid suitable for expression of the extracellular domain of TR2 was constructed as follows to immunize mice for the production of anti-TR2 mAbs. The Fc fragment was removed from TR2-Fclink by a BglII/XbaI digestion, Klenow was used to fill in the overhangs, and the blunt ends of the plasmid were religated. The resulting frame shift introduced a stop codon immediately following the amino acids which bad originally been introduced into TR2-Fclink by the addition of the BglII site. Thus, the C terminus of the extracellular domain of TR2 is followed by only 2 amino acids (RS) in this constructed (TR2exlink). 
 Purification of TR2-Fc from CHO ElA Conditioned Media Followed by Cleavage and Biotinylation of TR2. Assays Product purity through the purification was monitored on 15% Laemmli SDS-PAGE gels run under reducing and non-reducing conditions. Protein concentration was monitored by A280 assuming an extinction coefficient of 0.7 for the receptor and 1.28 for the chimera, both calculated from the sequence. Extinction coefficients were confirmed by AAA. Protein G Chromatography of the TR2-Fc Fusion Protein All steps described below were carried out at 4° C. 15 L of CHO conditioned media (CM) (0.2 &mgr; filtered following harvest in cell culture) was applied to a 5×10 cm column of Protein G at a linear flow rate of 199 cm/h. The column had been washed with 100 mM glycine, pH 2.5 and equilibrated in 20 mM sodium phosphate, 150 mM sodium chloride, pH 7 prior to sample application. After the CM was loaded the column was washed with 5 column volumes of 20 mM sodium phosphate, 150 mM sodium chloride, pH 7 and eluted with 100 mM glycine, pH 2.5. 435 ml of eluate was immediately neutralized with 3 M Tris, pH 8.5 and 0.2 &mgr; filtered. Based on A280, extinction coefficient 1.28, 65 mg of protein was recovered at 0.15 mg/ml. Concentration/Dialysis 385 ml of Protein G eluate was concentrated in an Amicon stirred cell fitted with a 30K membrane to 34 nl at a final concentration of 1.7. The concentrate was dialyzed against buffer. Factor Xa Cleavage and Purification to Generate Free Receptor Six ml (10.2 mg) of TR2-Fc was added to 50 &mgr;g of Factor Xa resulting in a 1:200, e:s ratio. The mixture was incubated overnight at 4° C. Protein G Chromatography of the Free TR2 receptor A 1 ml column of Protein G was equilibrated in 20 mM sodium phosphate, 150 mM sodium chloride, pH 6.5 in a disposable column using gravity flow. The cleaved receptor was passed over the column 3 times after which the column was washed with 20 mM sodium phosphate, 150 mM sodium chloride, pH 6.5 until no A280 absorbance was seen. The column was eluted with 2.5 ml of 100 mM glycine, pH 2.5 neutralized with 83 el of 3 M Tris, pH 8.5. TR2 eluted in the nonbound fraction. Concentration The nonbound fraction from the Protein G column, about 12 ml, was concentrated in a Centricon 10K cell (Amicon) to about 1 ml to a final concentration of 3.5 mg/ml estimated by A280, extinction coefficient 0.7. Mono S Chromatography The concentrated sample was diluted to 5 ml with 20 mM sodium phosphate, pH 6 and applied to a 0.5×5 cm Mono S column equilibrated in 20 mM sodium phosphate, pH 6 at a linear flow rate of 300 cm/h. The column was washed with 20 mM sodium phosphate, pH 6 and eluted with a 20 column volume linear gradient of 20 mM sodium phosphate, pH 6 to 20 mM sodium phosphate, 1 M sodium chloride, pH 6. TR2 protein eluted in the nonbound fraction. Concentration/Dialysis The 3 ml nonbound fraction from the Mono S column was concentrated to 1 ml as above using a Centricon 10K cell and dialyze against 20 mM sodium phosphate, 150 mM sodium chloride, pH 7. The concentration following dialysis was 2.1 mg/ml. Biotinylation 0.5 mg of TR2 at 2.1 mg/ml was dialyzed against 100 mM borate, pH 8.5. A 20-fold molar excess of NHS-LC Biotin was added and the mixture was left on a rotator overnight at 4øC. The biotinylated TR2 was dialyzed against. 20 mM sodium phosphate, 150 mM sodium chloride, pH 7, sterile filtered and stored at −70øC. Biotinylation was demonstrated on a Western blot probed with strepavidin HRP and subsequently developed with ECL reagent. Monoclonal antibody generation Mice (F1 hybrids of Balb/c and C57BL/6) were immunised subcutaneously with 10 ug recombinant TR2 in Freunds complete adjuvant and 4 weeks later with 10 ug TR2 in Freunds incomplete adjuvant. On the basis of a good serum antibody titre to TR2 one mouse received further immunisations of 8 ug TR2 (i.p. in saline) at 8 weeks, and two days later. Two days following the final immunisation a splenectomy was performed. Mouse spleen cells were used to prepare hybridomas by standard procedures, (Zola, H.Ed., Monoclonal Antibodies, CRC Press Inc. 1987). Positive hybridomas were cloned by the limiting dilution method. Hybridoma Screening Assay 96-well plates were coated with TR2-Fc (0.25 ug/ml, 100 ul/well in PBS) by incubation overnight at 4° C. The solution was then aspirated and non-specific binding sites were blocked with 250 ul/well of 1% bovine serum albumin (BSA) in TBS buffer (50 mM Tris, 150 mM NaCl, 0.02% Kathon, pH 7.4) for 5-60 minutes at RT. Following this and each of the following steps, the plate was washed 4 times in wash buffer (10 mM Tris, 150 mM NaCl, 0.05% Tween 20, 0.02% Kathon, pH 7.4). To each well, 50 uL hybridoma medium and 50 uL assay buffer (0.5% BSA, 0.05% bovine gamma globulin, 0.01% Tween 40, 20 uM diethylenetriaminepentaacetic in TBS buffer) was added and the plates were incubated for 60 min at RT in a shaker-incubator, followed by an incubation of 60 min at RT in a shaker-incubator with 100 ul 0.5 ug/ml Eu 3&plus; labelled anti-mouse antibody in assay buffer. Finally 100 ul /well of enhancer (Wallac) was added and incubated for 5 min at RT and the fluorescence measured. Hybridomas having counts >100K were expanded into 24-well plates. Immunoassay To determine the specificity of the anti-TR2 Mabs generated 96-well plates were coated (1 ug/ml TR2-Fc, 100 ul/well) and blocked as above with TR2-Fc. All the following incubations were performed in a shaker-incubator at RT. After washing the wells 50 ul TR2 (2 ug/ml), TR2-Fc (2 ug/ml), hIgG (2 ug/ml) or assay buffer and 50 ul Mab were added and incubated for 60 min. After washing the wells 100 ul 0.5 ug/ml Eu 3&plus; labelled anti-mouse antibody in assay buffer was added for 60 min, the wells washed and then 100 ul /well of enhancer (Wallac) was added and incubated for 5 min at RT and the fluorescence measured. All positive hybridomas showed displacement of binding with TR2 and TR2-Fc and none with hIgG. Purification of Mabs Mabs were purified by ProsepA (Bio Processing) chromatography respectively using the manufacturer's instructions. Mabs were >95% pure by SDS-PAGE. Biosensor Studies Surface plasmon resonance (SPR) technology (BIAcore) was used to analyse the epitope specificity and affinity of the TR2 Mabs. 18D4 and 12C5 have simnilar/overlapping epitopes 
 Summary of Binding Data 
 Epitope Determination of TR2 mAbs and Affinity Measurements by Surface Plasmon Resonance (SPR) Measurements Using a BIAcore Device 1 mAb K ass × 10 −5 (M −1 s −1 ) K diss × 10 4 (s −1 ) calc. K D (nM) 12C5 5.9 5.4 0.91 18D4 0.57 10 18 The TR2-Fc was immobilized onto the sensor surface. Solutions of the mAbs were passed over the surface. Equilibrium responses at each mAb concentration were calculated from the kinetic data (see attachment). The different maximal responses of the mAbs suggest they bind to different epitopes. The “affinities” of the mAbs appear good for the TR2-Fc but may be considerably lower for an expressed monomeric receptor. The association rate constant is lower than usually seen for most mAbs. Maybe this is a clue. 
 Binding of TR2 mAb 18D4 to Activated Human CD4 &plus; T Cells Monoclonal antibodies 18D4 were tested for reactivity on freshly isolated activated CD4 &plus; T cells. CD4&plus; T cells were purified from human peripheral blood by ficoll density gradient centrifugation, the depletion of B lymphocytes and monocyte/macrophages in T cell columns (R&D Systems) and subsequent depletion of CD8 &plus; T cells using immunomagnetic CD8 dynabeads (Dynal). Cells were stimulated with PHA (5 ug/ml) and PMA (10 ng/ml) for 72 hours in RPMI 1640 medium supplemented with 10% fetal calf serum, 2 mM L-Glutarnine, 50 ug/ml Gentomycin and 25 mM Hepes buffer. Activated cells were incubated with different concentrations of TR2 mAb 18D4for 30 minutes at 4° C., washed twice in PBS containing 0.2% BSA and 0.1% Sodium Azide (Staining buffer) and incubated for another 30 minutes at 4° C. with Goat anti-mouse FITC labelled antibody. Cells were washed three times and fixed in staining buffer containing 2% Formaldehyde. Samples were subsequently analysed on a Becton Dickinson FACSort using Cellquest software. Specific binding to 72 hour activated CD4 &plus; T cells was demonstrated for the TR2 mAb. Optimal binding was seen at 100 ug/ml for 18D4. This data indicates that TR2 is expressed on the surface of activated CD4 &plus; T cells and that the TR2 mAb 18D4 binds to this molecule. 
 Kinetics of TR2 Expression on Activated CD4 &plus; T Cells Human peripheral blood CD4 &plus; T cells were isolated using density gradient centrifugation, T cell columns (R&D Systems) and depletion of CD8 &plus; T cells using immunomagnetic CD8 beads (Dynal). Cells were activated using immobilised anti-human CD3 mAb (1 ug/ml) in RPMI 1640 medium supplemented with 10% fetal calf serum, 2 mM L-Glutamine, 10 ug/ml Gentomycin and 25 mM Hepes buffer. At 24 hour intervals activated cells were incubated with TR2 mAbs for 30 minutes on ice, washed twice in PBS containing 0.2% BSA and 0.1% Sodium Azide (Staining buffer) and incubated for another 30 minutes with Goat anti-mouse FITC labelled antibody. Cells were washed three times and fixed in staining buffer containing 2% Formaldehyde. Samples were subsequently analysed on a Becton Dickinson FACSort using Cellquest software. TR2 mAb 18D4 showed moderate levels of binding to resting CD4 &plus; T lymphocytes but after 24 hours of stimulation with immobilised anti-CD3 mAb 18D4 binding decreased to low levels. After 48 hours, levels of TR2 cell surface expression increased to maximal levels before declining slightly at 72 hours. This data suggests that TR2 is expressed on resting CD4 &plus; T cells and following anti-CD3 stimulation cell surface expression of TR2 increases to maximal levels by 48 hours. 
 Inhibition of Mixed Lymphocvte Proliferation by TR2 mabs Peripheral blood T cells express TR2 and the role of this receptor in T cell activation was examined using a mixed lymphocyte reaction (MLR) proliferation assay. Peripheral blood mononuclear cells (PBMCs) from three healthy donors were purified by density gradient centrifugation. PBMCs from two donors were adjusted to 1×10 6 cells/ml in RPMI 1640 medium supplemented with 10% fetal calf serum, 2 mM L-Glutamine, 50 ug/ml Gentomycin and 25 mM Hepes buffer. PBMCs from the third donor were adjusted to 2×10 5 cells/ml. Fifty microliters of PBMCs from each donor were added to wells of a 96 well round bottomed microtitre plate. Dilutions of TR2 mAbs 12C5 and 18D4, anti-human CD4 mAb and control anti-hIL-5 mAb 2B6 were added in quadruplicate to the plate. Cells were cultured for 6 days at 37 ° C. in 5% CO 2 and 1uCi of 3 H thymidine was added to wells for the last 6 hours of culture. Cells were harvested using a Skatron cell harvester and 3 H thymidine incorporation was determined using a Wallac 3 scintillation counter. Positive control anti-CD4 mAb inhibited MLR proliferation at all concentrations tested (0.5-100 ug/ml) whereas negative control mAb 2B6 failed to inhibit allogeneic proliferation. TR2 mAb 12C5 inhibited allogenic proliferation from 0.4-100 ug/ml. In comparison, TR2 mAb 18D4 inhibited proliferation from only 25-100 ug/ml. A primary component of MLR proliferation can be attributed to T cells as shown by inhibition with the anti-CD4 mAb. This data suggests that TR2 mAbs 12C5 and 18D4 inhibit allogenic proliferation responses and indicates that TR2 is involved in T cell activation. 
 TR2 mAbs Inhibit Anti-CD3-Stimulated CD4±T Cell Proliferation and TNF Alpha Production The capacity of TR2 Mabs to interfere with anti-CD3 driven CD4 &plus; T cell proliferation was examined. In addition, secreted TNFa levels were also determined. Human peripheral blood CD4 &plus; T cells were isolated by density gradient centrifugation, T cell columns and depletion of CD8 &plus; T cells using magnetic CD8 dynabeads. Purified CD4 &plus; T cells were adjusted to 1×10 6 cell/ml in RPMI 1640 medium supplemented with 10% fetal calf serum, 2 mM L-Glutamine, 50 ug/ml Gentomycin and 25 mM Hepes buffer. 96 well flat bottomed microtitre plates with immobilised anti-CD3 mAb (5 ug/ml) received 10 ul of cell suspension, 50 ul of either TR2 mab 12C5 or 18D4 dilutions and 50 ul of medium in quadruplicate. Cells were incubated at 37° C. in 5% CO 2 . After 48 hours, 100 ul of supernatant was removed and pooled for each quadruplicate. 100 ul of fresh medium was then added back to each well. Cells were cultured for another 24 hours and 1 uCi of 3 H thymidine was added to wells for the last 6 hours of culture. Cells were harvested using a Skatron cell harvester and thymidine incorporation was determined using a Wallac &bgr; scintillation counter. Supernatant TNFa levels were determined using ELISA detection kit for human TNFa (R&D Systems) Both TR2 mAbs 12C5 and 18D4 inhibited anti-CD3 induced CD4 &plus; T proliferation. 18D4 inhibited proliferation from 0.025-100 ug/ml whereas 12C5 showed activity from 0.0062-100 ug/ml suggesting that 12C5 was more active than 18D4. Complete inhibition of proliferation was seen with both mabs between 25 and 100 ug/ml. Mabs 18D4 and 12C5 inhibited CD4 &plus; T cell proliferation with IC 50 's of 8 nM and 0.5 nM, respectively. TNFa levels in culture supernatants followed a similar pattern, with 12C5 and 18D4 showing a dose dependent inhibition of TNFa production. 18D4 appeared to be more active than 12C5 at inhibiting TNFa production. Both TR2 mAbs completely suppressed TNFa production at 100 ug/ml. This data suggests that TR2 mAbs 12C5 and 18D4 are capable of inhibiting anti-CD3-stimulated CD4 &plus; T cell proliferation and the production of TNFa indicating that TR2 is involved in modulating T cell proliferative responses and the production of T cell derived pro-inflammatory cytokines. 
 TR2 mAbs Inhibit Anti-CD3 and Anti-CD28-Stimulated CD4 &plus; T Cell Proliferation. TNFa and IL-2 Production The capacity of TR2 Mabs to interfere with anti-CD3 and anti-CD28 driven CD4 &plus; T cell proliferation was examined. In addition, the effect of TR2 Mabs on secreted TNFa and IL-2 levels were also determined. Human peripheral blood CD4 &plus; T cells were isolated by denisty gradient centrifugation, T cell columns and depletion of CD8 &plus; T cells using magnetic CD8 dynabeads. Purified CD4 &plus; T cells were adjusted to 1×10 6 cell/ml in RPMI 1640 medium supplemented with 10% fetal calf serum, 2 mM L-Glutamine, 50 ug/ml Gentomycin and 25 mM Hepes buffer. 96 well flat bottomed microtitre plates with immobilised anti-CD3 mAb (5 ug/ml) received 100 ul of cell suspension, 50 ul of either TR2 mab 12C5 or 18D4 dilutions and 50 ul of anti-CD28 mAb in quadruplicate. Cells were incubated at 37° C. in 5% CO 2 . After 48 hours, 100 ul of supernatant was removed and pooled for each quadruplicate. 100 ul of fresh medium was then added back to each well. Cells were cultured for another 24 hours and 1 uCi of 3 H thymidine was added to wells for the last 6 hours of culture. Cells were harvested using a Skatron cell harvester and thymidine incorporation was determined using a Wallac &bgr; scintillation counter. Supernatant TNFa and IL-2 levels were determined using ELISA detection kits for human TNFa and IL-2 (R&D Systems). Both TR2 mAbs 12C5 and 18D4 inhibited anti-CD3 and CD28 mAb induced CD4 &plus; T proliferation. 18D4 inhibited proliferation from 1.5-100 ug/ml whereas 12C5 only showed activity from 25-100 ug/ml. Complete inhibition of proliferation was seen with both mabs at 100 ug/ml. Mabs 1 8D4 and 12C5 inhibited CD3/CD28 stimulated proliferation with IC 50 's of 93 and 780 nM, respectively. TNFa levels in culture supernatants followed a similar pattern, with 12C5 and 18D4 showing a dose dependent inhibition of TNFa production. 18D4 appeared to be more active than 12C5 which correlated with the capacity of these mAbs to inhibit proliferation. A similar dose dependent inhibition of IL-2 production by both TR2 mAbs was also observed, with no detectable IL-2 present in cells treated with 100 ug/ml TR2 mAb. This data suggests that TR2 mAbs 12C5 and 18D4 are capable of inhibiting CD4 &plus; T cell proliferation and the production of cytokines such as TNFa and IL-2. This indicates that TR2 is involved in T cell proliferative responses, pro-inflammatory cytokine production and mitogenic T cell cytokine production. 
 TR2 mAbs Inhibit in vitro IgE Production in Response to IL-4 and Anti-CD40 mAb The capacity of TR2 mAb 12C5 to inhibit human IgE production was examined. Human peripheral blood mononuclear cell (PBMCs) were purified by density gradient centrifugation and adjusted to 1.25×10 6 cells/ml in HB 101 medium supplemented with insulin (5 ug/ml), transferrin (5 ug/ml) and selenious acid (5 ng/ml), 10% Fetal calf serum, 2 mM L-glutamine, 25 mM Hepes and 50 ug/ml gentomycin. 50 ul of anti-CD40 mAb (0.2 ug/ml final) and 50 ul of hIL-4 (3 ng/ml final), 100 ul of TR2 mAb and 800 ul of cell suspension were added to were added to wells of a 48 well flat bottomed microtitre plates in triplicate. Controls included anti-CD40 and IL-4 alone, medium and IL-4 alone. Cells were cultured for 14 days at 37° C. in 5% CO2. 700 ul of supernantant from individual wells were harvested and stored at −20° C. Supernantants were assayed for human IgE using a human IgE ELISA detection assay. Briefly, Immunlon II ELISA plates were coated with Rabbit anti-human IgE antibody (Dako) in PBS containing 0.02% Sodium Azide at 4° C. overnight. Plates were washed 4 times with PBS containing 0.05% Tween 20 and 0.02% Sodium Azide (wash buffer). Plates were blocked for 60 minutes at 37° C. with PBS containing 0.1% gelatin and 0.02% Sodium Azide. After 4 washes using wash buffer, 100 ul of IgE standard or sample diluted in PBS containing 0.1% gelatin, 0.02% Sodium Azide and 0.5% Tween 20 (assay buffer) were added to wells in duplicate and incubated at 37° C. for 60 minutes. Plates were washed and incubated with monoclonal mouse anti-human IgE (Serotec) for 60 minutes at 37° C. in assay buffer. After washing the plates Goat anti-mouse antibody conjugated to alkaline phosphatase in assay buffer was added to each well and incubated at 37° C. for 60 minutes. Plates were washed and 100 ul of p-nitrophenyl phosphate (1 mg/ml) in substrate buffer containing diethanolamine was added to each well. Plates were allowed to develop and optical densities read at 405 nm on an ELISA plate reader. In two separate experiments using 3 different donors, IgE production by PBMCs were inhibited by TR2 mAb 12C5 in a dose dependent manner. IC 50 values for the three donors were calculated to be <3 nM, 30 nM and 5 nM, respectively. These results indicate that TR2 mAb 12C5 is capable of inhibiting IgE production in response to hIL4 and anti-CD40 mAb. This suggests that the TR2 receptor is involved directly or indirectly in regulating PBMC IgE production in response to IL4 and anti-CD40 mAb.