bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of autologous mixed lymphocyte reaction by aggregated IgG molecules
Authors: Kabelitz Dieter , Canonica Giorgio Walter , Sjöberg Olof , Klareskog Lars , Wigzell Hans
Published: February 2007

Human autologous and allogeneic mixed lymphocyte reactions (MLR) were studied using various T cell subsets as responding cells. T cells expressing Fcγ receptor for IgG (TG) were weak responder while T cells with Fcμ receptor and T cells lacking Fc receptor responded vigorously in both types of MLR. Percoll‐separated T cells of low density (TL) enriched for TG cells were, however, excellent responders in autologous MLR, whereas T cells of high density (TH) were the major responders in allogeneic MLR. Continuous presence of or short‐term pulse with aggregated IgG significantly reduced the autologous MLR of unfractionated T and TL cells while largely sparing proliferation in allogeneic MLR. These findings are discussed with respect to diminished autologous MLR reactivity in certain autoimmune diseases.
Fine antigenic specificity and genetic restriction of lysozyme‐specific suppressor T cell factor produced by radiation leukemia virus‐transformed suppressor T cells
Authors: Adorini Luciano , Doria Gino , Ricciardi‐Castagnoli Paola
Published: February 2007

Culture supernatants obtained from a radiation leukemia virus‐transformed, hen egg‐white lysozyme (HEL)‐specific, suppressor T cell line are able, when injected into mice, to specifically suppress the anti‐HEL antibody response. Suppression is observed on both primary and secondary anti‐HEL antibody responses evaluated by direct and developed hemolytic plaque assays. Culture supernatants from this HEL‐specific suppressor T cell line do not suppress the antibody response induced by a structurally related lysozyme, demonstrating the presence in the culture supernatant of a suppressor factor endowed with fine antigenic specificity. The suppressor factor is able to selectively suppress the anti‐HEL antibody response induced by the N‐terminal C‐terminal peptide of the HEL molecule indicating that the fine specificity of this factor is restricted to an antigenic epitope present in this region of the HEL molecule. The suppressive activity is restricted by genes located within the H‐2 complex and analysis of the suppression induced in recombinant mice demonstrates that the interaction between HEL‐specific suppressor T cell factor and its cellular target requires identity in the I‐J region of the H‐2 complex.
B cell subpopulations in the mouse: Analysis with monoclonal antibodies NIM‐R2 and NIM‐R3
Authors: Chayen Ann , Parkhouse R. M. E.
Published: February 2007

Two rat monoclonal antibodies, NIM‐R2 and NIM‐R3, have been produced using the rat myeloma line 210RCY3‐Agl.2.3 and spleen cells from Lou rats immunized with mouse spleen cell plasma membrane or cells. The antibodies identify nonoverlapping populations of surface Ig‐positive cells in the spleen and a large (95%) proportion of bone marrow cells. Both recognize differentiation antigens in that the surface representation of the markers changes during the development of the cell. The NIM‐R3 specificity does not appear until three weeks of age in both the spleen and bone marrow and may be on a more mature set of cells. In contrast, the NIM‐R2 antibody, which stains the pre‐B cell line 70Z/3 and binds to neonatal cells, may recognize pre‐B cells in the bone marrow.

There was no Clear‐cut correlation between the presence or absence of surface IgM, surface IgD or complement receptors on B cells positive or negative for either NIM‐R2 or NIM‐R3. Most interesting was the finding of identical total surface Ig densities on cells which stained weakly or strongly with NIM‐R2, since these two B cell sub‐populations are shown to be enriched for memory and virgin B cells, respectively. To bias the production of monoclonal antibodies to distinct populations of cells, the immunogen for the NIM‐R3 fusion was depleted of cells strongly reactive with NIM‐R2. This method is of general applicability in the production of monoclonal antibodies to complementary populations of cells.
Recognition of self, balance of growth and competition: Horizontal networks regulate immune responsiveness
Authors: Grossman Zvi
Published: February 2007

This report addresses itself to two fundamental questions: the generation of immunologic specificity, and the regulation of cellular growth. The classical clonal selection theory and later schemes involving lymphocyte networks or “circuits” postulate sets of specific “recognition” events which directly determine the nature of the immune response. An alternative principle is offered to apply to the analysis of immune phenomena: namely, that of a Darwinian dynamic selection among lymphocyte populations differing in their relative “fitness”. Incremental selection pressure upon a diverse population is, in theory, capable of producing a precisely specific outcome, and this can account for the fine specificity of the immune response.

The immune system is described in terms of “horizontal” networks. A network consists of lymphocyte clones regulated by feedback mechanisms which manifest cross‐reactivity, resulting in competition and selection. The relative “fitness” of clones within a network depends primarily on their growth capacities, as assessed by the “balance of growth” hypothesis: accordingly, the number of divisions of an antigen‐responsive lymphocyte and the probability of maturation depend on regulatory factors. In particular, (a) activated, but not “resting” cells, can be further induced to mature or regenerate the relative probability of maturation increases with antigen dose and with affinity (avidity); (c) the in vivo induction of “terminal differentiation” of both B and T cells is antagonistic to clonal expansion; and (d) both activation and maturation are threshold‐dependent in terms of antigen dose and avidity, the threshold for maturation being generally higher. The hypothesis implies that proliferation can be uncoupled from differentiation under certain predictable conditions. Moreover, clones that proliferate for prolonged periods of time without significant maturation into effector cells may reach prominence. This mode of “latent proliferation” plays a major role in the selection and expression of the immune repertoire: those T or B cells are selected that react “proliferatively” with certain classes of self antigens and this constraint ensures tolerance to self. Major histocompatibility complex restriction and alloreactivity follow essentially as expressions of heteroclicity in this selection. Proliferative, latent reactions can mediate generation and maintenance of memory and tolerance and determine the ratio of helper to suppressor cells. The proposed scheme is amenable to testing and has many theoretical and experimental implications.
α‐Bungarotoxin binding to the nicotinic acetylcholine receptor is inhibited by two distinct subpopulations of anti‐receptor antibodies
Authors: Barkas Thomas , Gairns Jan Mcphail , Kerr Helen Jackson , Coggins John Richard , Simpson John Alexander
Published: February 2007

Affinity‐purified antibodies to the nicotinic acetylcholine receptor of Torpedo marmorata were fractionated into two populations using a covalently cross‐linked receptor‐toxin immunosorbent lacking free toxin‐binding sites.

The population of antibodies which bound to and were subsequently eluted from this resin, and which cannot possibly contain antibodies directed to the toxin‐binding site itself, was effective in inhibiting the binding of toxin to receptor in solution. This unequivocally demonstrates that inhibition of toxin binding can be mediated by antibodies which are not directed against the toxin‐binding site. A second minor population of antibodies which did not bind to the affinity resin but which did inhibit the binding of toxin to receptor in solution was detected.

Two subpopulations of toxin‐binding inhibitory antibodies can therefore be distinguished. A clear differentiation should be made in future work describing “anti‐toxin site” antibodies between antibodies directly binding to the toxin‐binding site and the pseudo‐anti‐toxin‐binding site antibodies described in this report.
Intrastrain recurrent idiotypes among anti‐DNA antibodies of (NZB X NZW)F1 hybrid mice
Authors: Tron François , Guern Christian Le , Cazenave Pierre‐André , Bach Jean‐François
Published: February 2007

Immunization of NZB and A/J mice against an anti‐DNA hybridoma antibody (F227) derived from (NZB x NZW)F1 (B/W) mice allowed the preparation of two anti‐idiotype antisera. These two reagents were shown to recognize different idiotopes of the F227 monoclonal antibody. NZB anti‐idiotypic antibodies recognized non‐ligand‐modifiable idiotypic determinants. These idiotopes were private or present at undetectable level in BW mouse sera since it was found that only two of the 24 B/W mouse sera tested were recognized by these antibodies. Conversely, A/J anti‐idiotypic antibodies recognized partially ligand‐modifiable idiotopes which were found in all B/W mouse sera tested. These results demonstrate that anti‐DNA antibodies share similar idiotypic specificities and suggest that these autoantibodies occur as families of structurally related proteins.
Development and continuous growth in culture of interleukin 2‐producer lymphocytes from athymic nu/nu mice
Authors: Palacios Ronald , Fernandez Carmen , Sideras Paschalis
Published: February 2007

Splenocytes of nu/nu mice treated with serum thymic factor (FTS) for 3 or more days followed by stimulation with either phorbol myristate acetate (PMA) or concanavalin A (Con A) produced interleukin 2 (IL2) as determined in two indicator systems, namely, support of growth of IL 2‐dependent T cells and promotion of Con A‐initiated mitogenesis of thymocytes. However, neither mitogens nor FTS alone could induce nude mice cells to produce IL2.

Supernatants derived from the tumor cell line WEHI‐3 (WEHI‐3 conditioned media) induced and supported continuous growth in culture of Thy‐1.2+, Lyt‐1+2− lymphocytes from athymic nude mice capable of producing IL2 after their stimulation by either, PMA or Con A. The growth of these IL 2‐producer cell lines strickly depends on the presence of WEHI‐3 conditioned media, as in the absence of it they die 24‐48 h later. In addition, WEHI‐3 conditioned media have been supporting the growth of IL 2‐producer cell lines derived from nude mice for 3 1/2 months.

The helper factor contained in WEHI‐3 conditioned media responsible for the above biological activity has an apparent mol. wt. of ∼ 40 000 as determined by Sephadex G‐100 chromatography and lacks IL1 and IL2 activities, but efficiently supports the growth of IL 2‐producer cells derived from nude mice and the peripheral blood of normal human volunteers. These results indicate that the helper factor in WEHI‐3 conditioned media which enables the generation and continuous proliferation in culture of IL 2‐producer cells in nude mice is distinct from interleukin 1, IL2 and FTS (mol. wt. 864). Finally, the possible functional relationship of FTS and the helper factor produced by WEHI‐3 cells is discussed.
The relationship between surface immunoglobulin isotype and immune function of murine B lymphocytes V. IgD‐bearing cells in immunological tolerance
Authors: Zan‐Bar Israel , Barzilay Malka
Published: February 2007

The role of IgD (δ) in the induction of tolerance in murine B lymphocytes was explored in the in vivo adoptive antibody response to bovine serum albumin (BSA). δ+ or δ− B cells purified on the fluorescence‐activated cell sorter were injected, with or without purified T cells, into lethally irradiated intermediate hosts, which were rendered tolerant by an injection of deaggregated BSA one day after the cell transfer. Spleen cells from the intermediate hosts were treated with anti‐Thy‐1.2 antiserum and complement mixed with normal T cells and were transferred to final hosts. The ability of the B cells of the final hosts to respond to the tolerogen BSA and to dinitrophenylated human gamma globulin antigen was examined. This approach enabled examination of the function of the B cell subpopulations in an environment free of tolerogen and of induced T suppressor cells.

The results revealed that in the presence of T cells the δ+ subpopulation was highly resistant to tolerance induction, whereas the δ− subpopulation was highly susceptible to tolerance induction. However, there was no difference in susceptibility to tolerance induction between the two subpopulations when tolerance was induced in the absence of T cells.
An influenza virus matrix protein‐specific human T cell line with helper activity for in vitro anti‐hemagglutinin antibody production
Authors: Fischer Alain , Nash Sue , Beverley Peter C. L. , Feldmann Marc
Published: February 2007

A human helper T cell line (F14m) activated by the matrix protein purified from A/X31 influenza virus has been developed. After activation by antigen for 7 days, and reculture with matrix protein and irradiated autologous feeder cells, the cells obtained from an in vivo influenza virus‐immunized donor have been growing in the presence of interleukin 2 for more than 7 months. The cells all belong to the helper‐inducer T cell subset and most of them express surface membrane HLA‐DR antigens. A small number (approximately 103) of F14m T cells provided optimal help for 1 × 105 autologous T‐depleted lymphocytes for production of anti‐A/X31 but not anti‐B/HK antibodies. The F14m T cells produce soluble factors (S14m) able to help B cells to secrete anti‐A/×31 antibodies. F14m and S14m were shown to help antibody production to hemagglutinin when cultured with B cells and the whole virus. The specificity of the T cell line for type‐A matrix protein was confirmed by the ability of S14m to provide help for anti‐A/JAP (A/H2/N2) but not for anti‐B/HK antibody production. These data provide evidence for matrix protein‐specific T helper cells and factors able to provide help for antibody production against hemagglutinin, a distinct protein of the same virus.
Selection of the T cell repertoire during ontogeny: Limiting dilution analysis
Authors: Teh Hung‐Sia , Bennink Jack , von Boehmer Harald
Published: February 2007

The relative frequencies of cytotoxic T lymphocyte precursors (CTL‐P) specific for minor histocompatibility antigens that are restricted to either k or b major histocompatibility complex antigens in normal B6 mice and in B6 → (B6 CBA)F1 radiation chimeras were estimated. The ratio of k‐restricted to b‐restricted CTL‐P determined for the radiation chimeras served as a base value to which the ratio of k: b‐restricted CTL from normal B6 mice can be compared. The frequencies of allorestricted CTL‐P in B6 mice were determined after the B6 cells had been depleted of k‐reactive cells by filtration through irradiated B6.H−2k mice. Lymphocytes from immunized animals were used to obtain frequency estimates of CTL‐P specific for minor H antigens. The cultures contained nu/nu spleen cells syngeneic to the responder, but no exogenous interleukin 2 (T cell growth factor) since a high degree of nonspecific killing was found in IL2‐supplemented cultures. It was found that the CTL‐P frequency of B6 mice to BALB.B antigens in the lymph node cells of normal or immune B6 mice were 1 in 300000 and 1 in 8000, respectively. In B6→ (B6 × CBA)F1 radiation chimeras, the ratio of BALB.B/BALB.K‐specific CTL‐P was 3 :1s ratio was 17 :1 in normal B6 mice. Twenty‐five percent of CTL clones from normal B6 mice lysing BALB.K target also lysed BALB.B target whereas less than 1% of CTL clones lytic on BALB.K target from the chimeras showed this cross‐reaction The results are compatible with the idea of complete positive selection of self MHC‐restricted CTL‐P in the absence of priming effects by foreign antigen.
Pre‐B cell differentiation in the bone marrow: A proliferative pathway parallels the post‐mitotic maturation of early B cells
Authors: Deslauriers‐Boisvert Nöella , Mercier Ginette , Lafleur Louis
Published: February 2007

Considerable heterogeneity was found in bone marrow B cell progenitors as functionally defined, size‐separated populations were analyzed for their density of membrane IgM receptors, their adherence potential to nylon wool fibers and their susceptibility to lipopolysaccharide‐induced differentiation to IgM secretion. The investigation of their cycling status with tritiated thymidine further permitted definition of resting and actively proliferating populations. Heterogeneity was found in the fraction of resting small cells as expected for early B cells progressing through postmitotic maturation. However, the data suggest that part of the pre‐B cell progeny can also mature during a proliferative phase.
Human lymphocyte proliferation II. Formation of activated (G1) cells
Authors: Bettens Florence , Kristensen Flemming , Walker Christoph , de Weck Alain L.
Published: February 2007

The kinetics of phytohemagglutinin (PHA)‐stimulated human peripheral blood lymphocytes in the early phases (G0, G1a, G1b) of the first cell cycle have been analyzed in vitro by cytofluorometry and [3H] thymidine incorporation. Cells were detected in the G1a G1b and S phases 12‐14, 20‐22 and 24‐26 h after stimulation, respectively. The total number of PHA‐induced G1 cells reached a plateau after 32 h of incubation, upon which a second increase followed, 10 h later. The latter increase was considered to be a result of cells initiating their second cell cycle, since it could be abolished by hydroxyurea.

By examination of supernatants, interleukin 2 (IL 2) activities could be recovered 6 10 h after PHA stimulation. In contrast, the monokine IL 1 was already detected after 2 h. Both interleukins were present in the culture medium before the major G1a, cell formation took place. The titer of free IL 2 increased to a maximum after 18‐22 h, whereafter a decline was observed. This decline was less pronounced if cultures were treated with hydroxyurea. Finally, among individual donors, the total number of lymphocytes entering the G1 phase and the time at which the G1a‐G1b transition took place varied. Lower numbers of G1 cells and delayed G1a‐G1b transition coincided with lower IL 2 titers and delayed occurrence of maximal titers in the supernatants.
Clonal differences in response to T cell replacing factor (TRF) for IgM secretion and TRF receptors in a human B lymphoblast cell line
Authors: Saiki Osamu , Ralph Peter
Published: February 2007

A number of human B lymphoblast cell lines were tested to find a suitable model for induction of immunoglobulin‐secreting cells (ISC) by T cell replacing factor (TRF). Partially purified TRF was size fractionated from the conditioned medium of irradiated (1000 rds) human spleen cells stimulated with pokeweed mitogen. IgM line SKW 6 showed high levels of TRF‐stimulated immunoglobulin secretion and was chosen for cloning experiments. Clone 11 had a very low level of ISC with or without TRF (less than 0.1% ISC). Clone 4 had low background numbers of ISC (0.2%) and showed the highest degree of stimulation by TRF (to 6% IFC). High secreting clone 8‐2 (6%) was not stimulated significantly by TRF. These clones had the same HLA‐DR antigens, and their levels of ISC and sensitivity to TRF were relatively stable over three months of observation. The TRF preparation also had strong helper activity for normal peripheral blood B cell differentiation. TRF activity for both normal B cells and clone 4 cell line was absorbed by all 3 clones, but not by a pre‐B line. This suggests that the effector molecules for normal B cell and cell line differentiation were the same. The three typical clones corresponding to nonresponding, responding, and high rate‐secreting B cells provide basic models for analyzing B cell receptors for TRF and the biochemical effects of TRF during B cell differ entiation.
Enhanced expression of human Ia antigens by chronic lymphocytic leukemia cells following treatment with 12‐O‐tetradecanoylphorbol‐13‐acetate
Authors: Guy Keith , Van Heyningen Veronica , Dewar Edna , Steel C. Michael
Published: February 2007

Using a panel of monoclonal antibodies which detect framework determinants of human‐Ia à and β polypeptides and the DC‐specific monoclonal antibody Genox 353, the in vitro effects of 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) on the expression of Ia antigens by cells from chronic lymphocytic leukemia (CLL) patients have been studied. In all subjects studied a great increase in expression of framework Ia determinants was found following culture of CLL cells for 90 h with TPA at 10−7 g/ml. TPA treatment of CLL cells also induced increased expression of Genox 353+ antigens, in some cases where Genox 353 binding was either negligible or not detectable in cells cultured in the absence of TPA.
Immunoglobulin isotype in the murine response to polysaccharide antigens
Authors: Moreno Carlos , Esdaile Jane
Published: February 2007

Murine antisera specific for the α (1→3) and α (1→6)‐linked glucosyl determinants of dextran, as well as for meningococcal polysaccharide group C, have been examined for the distribution of their immunoglobulin classes and subclasses. Whereas the thymus‐independent anti‐α (1→3) dextran response in BALB/c mice was found to be IgM > IgG3 > IgA, thus corresponding to previously published work, neither the α (1→6) response in its thymus‐dependent or‐independent form, nor the response to purified meningococcal polysaccharide, corresponded to this pattern. No preference for any of the IgG subclasses appeared for these antigens when given as thymus‐independent carbohydrates. On the other hand, thymus‐dependent forms of α (1→6) dextran showed an IgG1 > IgG3 > IgG2 pattern.
Effect of cyclosporin A on the induction and activation of B memory cells by thymus‐independent antigens in mice
Authors: Shidani Babak , Colle Jean‐Hervé , Motta Iris , Truffa‐Bachi Paulo
Published: February 2007

The effect of cyclosporin A on the induction and activation of B memory cells by thymus‐independent (TI) antigens was investigated. Studies were carried out in C57BL/6 mice, a strain in which TI.1 trinitrophenyl‐lipopolysaccharide (TNP‐LPS) and TI.2 dinitrophenyl‐(DNP)‐Ficoll antigens can elicit a secondary response. Evidence is presented that cyclosporin A does not adversely affect the primary or secondary response to TNP‐LPS. In contrast, this fungal metabolite prevents the triggering of virgin B lymphocytes and TNP‐LPS‐induced memory cells by DNP‐Ficoll. Cyclosporin A does not interfere with the generation of hapten‐specific B memory cells by TNP‐LPS or DNP‐Ficoll. These findings are discussed in terms of B cell lineages leading to antibody‐forming cell precursors and memory cells.
Characterization of a subpopulation in neonatal thymus which suppresses the graft‐vs.‐host reaction
Authors: Van Bekkum Dirk W. , Knaan‐Shanzer Shoshan
Published: February 2007

Thymus cells from neonatal and infant mice were found to have a high capacity to prevent mortality from acute graft‐vs.‐host disease as compared with spleen cells from stable radiation chimeras. This suppressive capacity of thymocytes decreases with age after birth as was demonstrated by semi‐quantitative cell titrations. This suppressor activity is restricted to syngeneity of the graft‐vs.‐host disease‐including cells. The thymic suppressor cells are Thy‐1+ and Lyt‐1+ and IgG− and IgM−. They do not agglutinate with peanut agglutinin and have a high electrophoretic mobility. In vitro irradiation experiments showed that the suppressor cells are radiation sensitive. These results are compared with the available information on cells suppressing delayed‐type hypersensitivity reactions and those suppressing B cell responses.
IgG subclass distributions in anti‐hapten and anti‐polysaccharide antibodies induced by haptenated polysaccharides
Authors: Sarvas Heikki O. , Aaltonen Leena M. , Péterfy Ferenc , Seppälä Ilkka J. T. , Mäkelä Olli
Published: February 2007

Mice were immunized with hapten [NIP, (4‐hydroxy‐5‐iodo‐3‐nitrophenyl)acetyl or TNP (2,4,6‐trinitrophenyl)] conjugates of Ficoll or pneumococcal polysaccharide type 14 (S14), and they were bled on days 10 or 14. Anti‐hapten and anti‐polysaccharide antibodies were determined from the sera or from fractions (IgM + IgA), IgG1, IgG2a, IgG3 or IgG2h separated by a gradual acid elution from protein A. Approximately one‐half of both anti‐hapten and anti‐polysaccharide antibodies was found in the IgM + IgA fraction. The subclass distribution of the IgG antibodies was dependent on the antigenic determinants. Polysaccharide antibodies were mostly in the IgG3 fraction (36–62%) and in the IgG1 fraction (18–36%). Hapten IgG antibodies were mostly in the IgG1 fraction (38–74%); each of the other three subclasses contributed the average of 13%. These results provide the first evidence that antibodies to different determinants of one antigen have grossly different isotype distributions.
Effect of anti‐γ3 antibodies on immunoglobulin isotype expression in lipopolysaccharide‐stimulated cultures of mouse spleen cells
Authors: Webb Carol F. , Gathings William E. , Cooper Max D.
Published: February 2007

To test the hypothesis that γ3 is the pivotal isotype for sequential heavy chain switching from μ to each of the γ isotypes, we have compared the effects of anti‐γ3 and anti‐μ antibodies on the expression of immunoglobulin isotypes in lipopolysaccharide (LPS)‐stimulated cultures of mouse spleen cells. IgM‐, IgG1‐, IgG2b‐ and IgG2a‐containing plasma cells were enumerated by immunofluorescence and secreted immunoglobulins were measured by radioimmunoassay. Although anti‐γ3 and anti‐μ, were equally effective in inhibiting the LPS‐induced differentiation of IgG3 plasma cells, anti‐γ3 had no effect on the differentiation of IgM, IgG1, IgG2b, or IgG2a plasma cells. These results support a direct mechanism of heavy chain immunoglobulin switching.
A functional homologue of mammalian secretory component exists in chickens
Authors: Peppard Jane V. , Rose M. Elaine , Hesketh Patricia
Published: February 2007

The existence of a molecule in chickens homologous to the secretory component of mammals has long been in dispute. An intravenous injection of [14C]fucose was given to chickens as a marker for newly synthesized glycoproteins and then unlabeled human IgA was injected intravenously half an hour later. It was shown that the human IgA subsequently appeared in the bile of the chickens combined with a [14C]fucose‐labeled molecule; the chicken IgA in these bile samples was similarly labeled. Radiolabeled human secretory IgA was not transported in large amounts across the chicken liver in vivo and neither was purified chicken bile IgA. These results indicate that a molecule exists in chickens which behaves in a manner analogous to mammalian secretory component.
The T3 complex on human thymus‐derived lymphocytes contains two different subunits of 20 kDa
Authors: Borst Jannie , Prendiville Mary Ann , Terhorst Cox
Published: February 2007

The human cell surface antigen T3 is involved in several T lymphocyte specific functions, as determined by the effect of monoclonal antibodies (OKT3, anti‐Leu‐4, UCHT1) directed at this molecular structure. The main target antigen of these monoclonal antibodies is a glycoprotein of 20 kDa. It is associated with four, less predominant, structurally distinct glycoproteins of 25‐28 kDa, 37 kDa and 44 kDa. Of these molecules only the 20‐kDa T3 antigen could be labeled with the hydrophobic reagent 5‐iodonaphthyl‐1‐azide (INA). Here we present evidence that the main 20‐kDa T3 antigen is comprised of, in fact, two structurally different molecules. One of these is a glycoprotein with a protein backbone of 14 kDa, the other is an unglycosylated protein of 20 kDa. This unglycosylated protein is labeled specifically with INA. Additional evidence for the existence of two different 20‐kDa T3 antigens is provided by studies using the enzymes endo‐β‐N‐acetylglucosaminidase H and endo‐β‐N‐acetylglucosaminidase F and the drug tunicamycin. We hypothesize that the specific susceptibility to labeling with INA of the unglycosylated 20‐kDa T3 form reflects a positioning in the lipid bilayer different from that of the glycosylated 20‐kDa T3 form.
Immunoglobulin expression in diploid and polyploid interspecies hybrids of Xenopus: evidence for allelic exclusion
Authors: Pasquier Louis Du , Hsu Ellen
Published: February 2007

The expression of species‐specific surface IgM was studied in various Xenopus species hybrids. Whether the hybrids are diploid or polyploid, a lymphocyte does not produce all of the immunoglobulins (Ig) encloded by the Ig genes present in its genome. This suggests that the selection pressure to make a lymphocyte synthesize only one antibody is high and that allelic exclusion already existed in the ancestors of amphibians which appeared 300 million years ago.

The apparent lack of cells producing multiple Ig in polyploid hybrids having more than one pair of functional Ig genes suggests that if a stochastic model for allelic exclusion is correct, the frequency of multiple successful rearrangements has to be very low, resulting in a huge waste of lymphocyte precursors. Given the particularity of frog development it is argued that this is not likely to be the case.
Ontogenic restriction of colonization of the bursa of Fabricius
Authors: Houssaint Elisabeth , Toraño Alfredo , Ivanyi Juvaj
Published: February 2007

The capacity of hemopoietic precursor cells (HPC) to home to embryonic bursal and thymic grafts was investigated in embryonic and newly hatched chickens. Whereas thymic grafts developed normal histogenesis in both types of recipients, the bursal rudiment was colonized and developed in embryonic, but not in newly hatched hosts. In the latter, noncolonized bursal grafts developed neither lymphoid follicles nor granulopoiesis in the mesenchyme. These results are interpreted in terms of ontogenic “maturation” of the HPC which lose their homing potential towards the bursa while they preserve their thymic seeding capacity. This hypothesis is consistent with previously reported data which indicated cyclic continuous recruitment of the thymic lymphoid population, but restricted bursal colonization to a relatively brief period of embryonic life.
Desensitization of macrophages to stimuli which induce secretion of superoxide anion. Down‐regulation of receptors for phorbol myristate acetate
Authors: Berton Giorgio , Gordon Siamon
Published: February 2007

The ability of cultivated mouse peritoneal macrophages (MΦ) to release superoxide anion (O2−) after repeated stimulation by phorbol myristate acetate (PMA) or serumtreated zymosan (STZ) has been studied. After a maximal first stimulus bacillus Calmette‐Guérin (BCG)‐activated MΦ released high levels of O2−, 2‐fold more than thioglycollate‐elicited MΦ and the response ceased within 4 h. Both populations either responded again to a second challenge or displayed a refractory state which varied in duration and selectivity. Desensitization by STZ pretreatment was transient and selective whereas PMA could render MΦ refractory for 3 days to PMA alone or to both agents, depending on the amount of PMA used and the conditions of stimulation. PMA induced a selective loss of specific saturable receptors for [3H]phorbol dibutyrate, a closely related agent, and receptor activity recovered with the ability to release O2−. Loss of receptors did not account for concomitant loss of the response to STZ after nonselective deactivation. Such MΦ were fully viable and able to endocytose various soluble and particulate ligands vigorously, but without stimulation of the hexose monophosphate shunt or release of O2−.

Our studies indicate that MΦ activities can be profoundly altered by prior stimulation, that specific receptors play a role in ligand‐induced desensitization and that agents such as PMA can selectively eliminate the cells′ ability to generate a second respiratory burst.
Mapping epitopes on the insulin molecule using monoclonal antibodies
Authors: Schroer Joyce A. , Bender Timothy , Feldmann Richard J. , Kim K. Jin
Published: February 2007

A panel of 18 monoclonal antibodies (mAb)Δ to insulin have been prepared and used to begin to map antigenic determinants on the insulin molecule. All 18 mAb were of the IgG class, with 14 IgG1, 2 IgG2a and 2 IgG2b. The affinities of these mAb for their immunizing insulin ranged from 1 × 106 to 3 × 108 1/M. The epitope recognized by three of the mAb, 1, 7 and 16 involves the three residues of the A chain, A 8‐10, the so called A chain‐loop determinant. This A chain loop is one of the most evolutionarily diverse regions of insulins from different species. Another mAb, 10, has been hypothesized to recognize a nearby epitope composed of the A chain residues, A4 and A8 and a B chain residue, B29, that are adjacent on the surface of the insulin molecule. Four of the mAb bind to synthetic B chain. The epitopes recognized by these 4 mAb and the last 10 mAb are unknown but the mAb are grouped according to their ability to bind to different species of insulin or proinsulin. The results of an 18 × 18 matrix analysis of pairs of mAb binding simultaneously to insulin indicate that, despite the finding that some mAb see similar antigenic sites on the insulin molecule, each of the mAb recognizes a unique site on the insulin molecule. Finally, a lower estimate of the number of possible antibodies made to insulin has been calculated to be ≧ 115, a number only 10‐fold lower than the lower limit of antibodies made to dinitrophenyl (DNP) or (4‐hydroxy‐5‐iodo‐3‐nitrophenyl)acetyl (NIP), following hapten protein immunization.
Differential requirements for activation and growth of unprimed cytotoxic and helper T lymphocytes
Authors: Gullberg Martin , Pobor Grgur , Bandeira Antonio , Larsson Eva‐Lotta , Coutinho Antonio
Published: February 2007

The requirements for activation and growth of T lymphocytes capable of mediating either cytolytic activity or help to B lymphocytes were studied in unprimed splenic T cell populations. The selectivity of expression of Lyt‐2 antigens, the reactivity to soluble concanavalin A (Con A), to partially purified interleukin 2 (IL2, T cell growth factor[s]) and to lectin‐pulsed macrophages (MΦ) were used in this analysis. Lectin‐dependent cytotoxicity assays and a novel method that allows for the detection of all effector helper cells, regardless of their clonal specificities, were used for the functional identification of the responding T cells.

The results show a marked contrast between cytolytic and helper T cells in their growth and activation requirements. Thus, while Lyt‐2+ cytotoxic T lymphocyte precursors grow exponentially in IL2 after a short pulse with soluble Con A in the absence of accessory cells, Lyt‐2− helper cell precursors completely fail to proliferate under the same conditions and require the continuous presence of lectin‐pulsed MΦ for significant growth. Furthermore, addition of IL2 to MΦ‐stimulated cultures of Lyt‐2− cells has no effect. T cells which produce IL2 have the same growth characteristics as helper cells. In both cases, effector helper functions could be expanded more than 10‐fold on a per cell basis by a 5‐day‐culture period under those growth supporting conditions. The development of effector helper functions, however, was strongly inhibited by the presence of Lyt‐2+ T cells.
The immune response against anti‐idiotope antibodies II. The induction of antibodies bearing the target idiotope (Ab3β) depends on the frequency of the corresponding B cells
Authors: Tesch Hans , Takemori Toshitada , Rajewsky Klaus
Published: February 2007

In the present study we use two monoclonal anti‐idiotope antibodies (Ac38 and Ac146; Ab1) against the germ line‐encoded, λ1 chain‐bearing and (4‐hydroxy‐3‐nitrophenyl)acetyl (NP)‐binding antibody Bl‐8 (Ab1) for the induction of complementary antibodies (Ab3) and ask the question to what extent antibodies bearing Bl‐8‐like idiotopes (Ab3β) are represented in the Ab3 population. In this experimental system, Ab3β is distinguished from the remaining Ab3 population (Ab3α) by three properties which Ab3β may share with Bl‐8: (a) the binding of NP, (b) the binding to Ac146 (if induced by Ac38) or the binding to Ac38 (if induced by 146) and (c) that they carry λ1 chains.

Antibodies with all three properties are induced in low amounts by both anti‐idiotopes. Also, Ac146 induces only Ab3α (bearing x chains and not binding NP and Ac38). In contrast, Ac38 triggers almost exclusively a λ1 chain‐bearing response, i.e. Ab3β. The response has an unusually large size, reaches its maximum after a week and is long‐lasting. An analysis at the level of lipopolysaccharide‐reactive precursor B cells demonstrates that, in this case, cells expressing Ab3β occur at exceedingly high frequency (≈ 10−3) and are at least 10 times more frequent than cells expressing Ab3α. The high frequency of Ab3β‐expressing cells correlates with the contribution of several VH, D and J genes to the expression of this particular idiotope. In the case of the Ac146 anti‐idiotope antibody, the response is dominated by Ab3α. Ab3β represents less than 10% of the total response, reaches maximal levels 2 weeks after immunization and declines rapidly. This correlates with a low frequency of precursor B cells expressing Ab3β (≈ 10−5) and a restriction of the corresponding idiotope to rare VH‐D combinations, caused presumably by a stringent contribution of the H chain to this idiotope which covers the NP‐binding site.

Our data suggest that anti‐idiotypic antibodies (Ab2) against Ab1 will preferentially induce antibodies idiotypically related to Ab1 if the corresponding idiotopes are expressed in high frequency in the B cell compartment. This is expected in cases where Ab2 recognizes an idiotope that can be formed by many germ line‐encoded VH‐D‐VL‐combinations.
Natural cytotoxicity in the mouse embryo: characterization of yolk sac‐associated natural cytotoxic cells and their activity
Authors: Dahl Carol A.
Published: February 2007

The natural cytotoxic activity of yolk sac (YS) cells from 10‐day mouse embryos against YAC‐1 tumor targets was characterized for its sensitivity to modulation by a variety of factors. Experiments demonstrated the observed levels of tumor cell lysis to be unaffected by the strain of origin of the YS cells, trypsin pretreatment of the YS population, as well as a prior stimulation by environmental pathogens. Both the YS natural cytotoxic (YSNC) activity and the adult natural killer (NK) cell activity were found to be depressed when assayed in the presence of amniotic fluid. YS cells were tested for antibody‐dependent cell‐mediated cytotoxic activity, but were not found to generate significant levels of lysis.

Experiments presented here demonstrate the YSNC activity to be dependent upon only a subpopulation of YS cells. The YSNC activity was found to be associated only with the cells exhibiting high forward angle light scatter as determined by flow cytometry. Additionally the activity was unaffected by the removal of plastic‐adherent cells from the effector population.

In this study, YSNC cells are also examined for the presence of a variety of lymphocyte antigens. The effector cells, as well as the total YS population, were found to lack Lyt‐1, Lyt‐2, Thy‐1, Ly‐5, NK‐1, Qa‐5, asialo GM1, and H‐2 antigens. While these experiments demonstrate the YSNC cells to be distinct from the NK cells of the adult, they do not rule out a potential common lineage for the two natural cytotoxic cell types.
Loss of serological determinants does not affect recognition of H‐2Kk target cells by an influenza‐specific cytotoxic T cell clone
Authors: Wraith David C. , Holtkamp Bodo , Askonas Brigitte A.
Published: February 2007

The recognition of “self determinants” by an H‐2Kk‐restricted cytotoxic T (Tc) cell clone (K5) has been investigated as follows: (a) differential inhibition of cytotoxicity by several monoclonal antibodies directed to determinants on the H‐2Kk molecule of the target cells and (b) recognition and lysis of target cell variants of cell line LDHB, which have lost the majority or all of the serological determinants defined by the inhibiting antibodies while still expressing an H‐2Kk molecule. Such variant cells infected with influenza virus were effectively recognized by Tc cell clone K5, whereas a target cell line, which lacks the Kk molecule, was not lysed. The results suggest; (a) that virus‐specific Tc cell see “self” in a manner distinct from the recognition of serological determinants by B cell and (b) that antibody inhibition indicates conformational closeness, but not identity, of the class I determinant seen by T cells.
Immune capacity of the chicken bursectomized at 60 hours of incubation: transplantation of bone marrow cells of the bursectomized chickens into cyclophosphamide‐treated newly hatched recipients
Authors: Jalkanen Sirpa
Published: February 2007

Chickens bursectomized at 60 h of incubation are known to be able to produce immunoglobulins (Ig) but not specific antibodies. In the present work bone marrow (BM) cells of 2‐ and 10‐week‐old embryonically bursectomized (Bx) chickens were transferred to newly hatched cyclophosphamide‐treated chickens for the purpose of studying whether the transplanted cells home into the bursa and gain a capacity to produce specific antibodies. BM cells of normal 2‐ and 10‐week‐old chickens were transferred as controls. Cells of 2‐week‐old control (Co) and of 2‐ and 10‐week‐old Bx chickens could to some extent reconstitute serum Ig of the recipients, but were totally incapable of homing into the bursa and of restoring the specific antibody production. Only BM cells of 10‐week‐old Co chickens could restore the production of specific antibodies without homing into the bursa, indicating their postbursal nature. These findings indicate (a) that 2‐ and 10‐week Bx BM cells have irreversibly bypassed the bursal phase of education, (b) that also the normal BM at the age of 2 weeks contains cells that are capable of Ig but not of specific antibody synthesis and (c) that bursal microenvironment is not necessary for isotype switch, but is essential for creation and expansion of the antibody repertoire.
Opposite effects of the synthetic immunodulator, muramyl dipeptide, on rejection of mouse skin allografts
Authors: Zídek Zdeněk , Čapková Jana , Boubelík Michal , Mašek Karel
Published: February 2007

The influence of muramyl dipeptide (N‐acetylmuramyl‐L‐alanyl‐D‐isoglutamine) on the rejection of mouse skin allografts was investigated. While the 0.1‐mg dose administered on days 7, 6, 5 prior to transplantation caused significant prolongation of the graft survival, the 0.5‐mg dose administered on days 3,2,1 prior to transplantation resulted in remarkable augmentation of the graft rejection. The present results support the view that muramyl dipeptide can induce both stimulatory and suppressive immune mechanisms, depending on the treatment regimen.
The specificity of H‐2‐restricted cytotoxic T lymphocytes directed to AKR/Gross leukemia virus‐induced tumors I. Isolation of a selectively resistant variant tumor subclone
Authors: Green William R.
Published: February 2007

The AKR.H‐2bSL1 tumor cell line is susceptible to H‐2Kb‐restricted cytotoxic T lymphocytes (CTL) directed against the subclass of AKR endogenous leukemia virus‐induced tumors that express the Gross cell surface antigen (anti‐AKR/Gross virus CTL). A variant subclone (cl.18‐5) of AKR.H‐2bSL1 was isolated, whose susceptibility to lysis by conventional or cloned lines of anti‐AKR/Gross virus CTL was approximately 5% or less than that of the parental tumor. The cl.18‐5 variant was also ineffective when used as an in vivo priming cell or an in vitro stimulator cell in the generation of anti‐AKR/Gross virus CTL or as an unlabeled target cell in competitive inhibition assays. These results implied that the failure of cl.18‐5 to be lysed was due to a lack of recognition by the CTL.

In contrast, cl.18‐5 was able to be lysed by and stimulate the generation of predominantly H‐2Db‐restricted CTL with apparent specificity for AKR minor histocompatibility antigens. The variant line was also about as susceptible as the parental AKR.H‐2bSL1 line to both allogeneic CTL and to H‐2Kb‐restricted, TNP‐specific CTL. Thus, the lack of recognition of cl.18‐5 by anti‐AKR/Gross virus CTL did not appear to be due to a failure to express functional H‐2 products or to a generalized insusceptibility to H‐2‐restricted CTL. Rather, cl.18‐5 appeared to be a selective variant and a useful probe for studying the specificity of anti‐AKR/Gross virus CTL.
Natural killer activity in (C57BL/6 × DBA/2)F1 hybrids undergoing acute and chronic graft‐vs.‐host reaction
Authors: Pattengale Paul K. , Ramstedt Urban , Gidlund Magnus , Örn Anders , Axberg Inger , Wigzell Hans
Published: February 2007

The present findings demonstrate that a total i. v. transfer of 100 × 106 C57BL/6 (B6) parental spleen cells into untreated (C57BL/6 × DBA/2)F1 hybrids (B6D2F1) resulted in acute runting, which was associated with a significantly elevated graft‐vs.‐host (GVH) index over a one‐month period following GVH induction. Furthermore, this B6‐induced acute GVH disease was associated with a marked depression of natural killer (NK) cell activity (spleen and peripheral blood) (with or without addition of mouse fibroblast interferon), which correlated with lymphoid cell hypocellularity, prominent splenic extramedullary hematopoiesis (EMH), and parallel depressions of both concanavalin A‐ and lipopolysaccharide‐induced mitogenesis. Significantly increased killing by antibody‐dependent cellular cytotoxicity of antibody‐coated chicken red blood cells, as well as increased T cell killing of the NK‐insensitive cell line P815 (as compared to the significantly decreased killing of the NK‐sensitive cell line YAC‐1) was also observed in the spleens of this 100 × 106 B6‐injected F1 group.

In marked contrast to this 100 × 106 B6‐injected acute GVH group, untreated mice injected i. v. with the same or greater numbers of parental DBA/2 spleen cells (100 × 106‐150 × 106 DBA/2 spleen cells) exhibited a milder and more chronic form of GVH disease, which was not associated with a significant decrease of NK activity. It was of considerable interest that a total i. v. transfer of 50 × 106 B6 spleen cells (i.e. one‐half of that required to produce acute GVH, markedly depressed NK, and prominent splenic EMH) into B6D2F1 hybrids also resulted in a more chronic form of GVH disease, but was associated with significantly increased levels of NK activity at two weeks post GVH induction.
Tolerance induction during ontogeny II. Distinct unresponsive states in immature mice question the generality of clonal abortion
Authors: Waters Cory A. , Diener Erwin
Published: February 2007

Multivalent trinitrophenyl (TNP) conjugates of both human γ‐globulin (HGG) and bovine serum albumin (BSA) are capable of inducing hapten‐specific unresponsiveness in neonatal mice, as assessed by challenge with TNP on thymus‐dependent carriers. When such mice are challenged with TNP on thymus‐independent carriers, however, only TNP‐HGG‐ but not TNP‐BSA‐treated mice are found to be substantially unresponsive to the hapten. Moreover, unresponsiveness induced by BSA, but not HGG, as a carrier was associated with the presence of antigen‐specific suppressor cells. Thus, contrary to predictions made by defendants of the classical clonal abortion hypothesis, functional deletion of hapten‐specific B cells appears to depend on the nature of the hapten‐carrier complex. This conclusion is supported by B cell‐precursor frequency estimates indicating that the number of hapten‐specific precursor cells is significantly lower in TNP‐HGG‐treated mice, but remains unaltered in TNP‐BSA‐treated mice relative to the precursor frequency in untreated animals. While it remains a formal possibility that the differences in tolerogenicity seen between the two carriers can be interpreted in terms of a difference in serum half‐life, we favor the interpretation that the distinction lies in molecular aspects of the carrier, which allow for differences in antigen handling by sets of interacting cells.