bluuebunny/crossref_metadata_2025 huggingface dataset:
Specific antigedantibody complexes induce the in vivo production of a parallel set of nonantigen‐binding idiotype‐positive antibodies
Authors: Caulfield Michael J. , Cerny Jan
Published: March 2007

Immune complexes prepared with the polysaccharide antigen (PnC) extracted from Streptococcus pneumoniae R36a and two different PnC‐specific antibodies were found to differ in their regulatory properties depending on the isotype of the antibody. Thus, complexes formed in antibody excess with TEPC15 (IgA) were suppressive whereas complexes formed with 96‐G (IgG3) antibodies enhanced the IgM response to PnC. During the course of these studies, we found that little or no PnC‐specific IgG antibody was induced during the response to PnC coupled to sheep red blood cells (PnC‐SRBC). Interestingly, however, immunization with 96‐G/PnC complexes either alone or with PnC‐SRBC resulted in the induction of IgG3 antibodies that express the TI5 idiotype (Id) but which do not bind PnC. This unique IgG3 response occurred after injection of 96‐G/PnC complexes formed in antibody excess but not when complexes were formed in antigen excess. The Id+ nonspecific IgG3 response peaked on day 5 and could be activated with 96‐G/PnC complexes but not with free PnC antigen. The Id+ nonspecific response was not due to polyclonal activation of IgG3 production since there was no difference in IgG3 levels in mice injected with 96‐G/PnC complexes with those injected with PnC‐SRBC. Finally, mice that had been suppressed for expression of the T15 Id by neonatal injection of anti‐Id antibody were able to produce Id+‐unspecific IgG3 antibody after immunization with 96‐G/PnC complexes, further suggesting that Id+ IgG3 was produced by different clones than those that usually comprise the antibody response to PnC. The results suggest that the formation of IgG immune complexes during an immune response may result in stimulation of idiotypically related clones thus resulting in degeneracy of the immune response.
The major surface protein of leishmania promastigotes is a fibronectin‐like molecule
Authors: Rizvi Farrukh S. , Ouaissi Mohamed Ali , Marty Béatrice , Santoro Ferrucio , Capron André
Published: March 2007

The major surface glycoprotein of Leishmania chagasi promastigotes showed cross‐reactivity with fibronectin (Fn), a large glycoprotein that is a major constituent of the extracellular matrix of most mononuclear cells. Polyclonal and monoclonal antibodies against Fn precipitated two molecules of 63‐58 kDa from the lysates of both 125I and [35S]methionine‐labeled promastigotes. In addition, a monoclonal antibody against a 15‐kDa fragment of Fn containing the Arg‐Gly‐Asp‐Ser (RGDS) sequence and several polyclonal monospecific mouse antibodies against a synthetic RGDS peptide also recognized the above two molecules. The attachment of Leishmania promastigotes to mouse peritoneal macrophages in vitro was partially inhibited when promastigotes were treated with F(ab')2 fragment of an anti‐Fn IgG. Identical results were obtained by saturating the Fn receptors on macrophages using different peptides containing the RGDS sequence. Moreover, antigen preparations rich in glycoprotein 63 could efficiently promote the attachment and spreading of 3T3 mouse fibroblasts to surfaces coated with the antigen. These results clearly suggest that the gp63 of L. chagasi promastigotes is an Fn‐like molecule that shares certain biological and molecular characteristics with Fn.
A cd3− subset of cd4−8+ thymocytes: a rapidly cycling intermediate in the generation of cd4+8+ cells
Authors: MacDonald H. Robson , Budd Ralph C. , Howe Rawleigh C.
Published: March 2007

T lymphocytes with the surface phenotype CD4+8− and CD4−8+ are considered to be representative of functionally mature cells. We show here that adult murine thymus contains a subpopulation of CD4‐8+ cells that differ from CD4−8+ cells found d the periphery in that they do not express the T cell receptor‐associated CD3 molecular complex. Such CD3−4−8+ thymocytes are cortisone sensitive and rapidly cycling in situ. Furthermore, in contrast to mature T cells, most CD3−4−8+ thymocytes express low levels of CD5 and high levels of the B2A2 antigen. CD3−4−8+ thymocytes fail to respond to a variety of mitogenic stimuli in vitro but do give rise upon short‐term culture to CD4+8+ cells. It is suggested that CD3−4−8+ thymocytes represent a transitional stage of thymus differentiation between the CD4−8− and CD4+8+ compartments.
T cell epitopes in experimental autoimmune myasthenia gravis of the rat: strain‐specific epitopes and cross‐reaction between two distinct segments of the α chain of the nicotinic acetylcholine receptor (torpedo californica)
Authors: Zhang Yiping , Barkas Tom , Juillerat Marcel , Schwendimann Bernhard , Wekerle Hartmut
Published: March 2007

T cell epitopes on the nicotinic acetylcholine receptor (AChR) of Torpedo californica were analyzed using T cell lines isolated from Lewis, BN, and (Lewis x BN)F1 rats. All lines selected for reactivity against either native or denatured AChR or for 6 selected synthetic peptides of the AChR α chain expressed the CD4 membrane phenotype and recognized their antigen in the context of major histocompatibility complex class II determinants. They were tested in vitro for reactivity with each of these antigens. The results indicate that parental Lewis and BN rat T lymphocytes recognize distinct molecular epitopes on the AChR protein, whereas (Lewis X BN)F1 hybrids respond against both sets of epitopes.

Two peptides (P10 and P11) which represent distinct amino acid sequences on the putatively extracellular part of the AChR α chain, and which share only 4 common amino acids, two of them contiguous, showed an unexpected cross‐reactivity in the Lewis rat. T cells selected for either peptide co‐recognize the other peptide in vitro. In addition, these cells are responsive against full length AChR. P11, in particular, appears to be a major epitope for Lewis rats immunized with AChR.
Inverse correlation between the utilization of an idiotype in specific immune responses and its representation in pre‐immune “natural” antibodies
Authors: Portnoi Denis , Lundkvist Inger , Coutinho AntÓNio
Published: March 2007

Previously we have characterized an idiotype (Id) that accounts for half of all specific anti‐dextran B512 (Dex) antibodies in C57BL/6 mice. BALB/c mice produce the same Id in normal, pre‐immune sera but fail to use it in antibody responses to Dex, although Id+ anti‐Dex antibodies can be induced in this strain by anti‐Id immunization. By limiting dilution analysis of B cellclonal precursors, we show here that the frequencies of Id+ B cells are comparable in both strains, but their state of activity is sharply distinct: while all Id+ B cells are small, resting lymphocytes in C57BL/6 mice, they are all large, naturally activated cells in BALB/6 mice. The suggestion that naturally activated cells are poorly engaged in specific responses was supported by the delayed and lower Id+ responses obtained in BALB/c mice when they are immunized, in parallel with C57BL/6 animals, with a conjugate of anti‐Id antibodies and lipopolysaccharide. Finally, C57BL/6 responder mice were found to closely reproduce the normal BALB/c situation, if analyzed 3 months after anti‐Id priming: they produce low levels of serum Id and all Id+ B cells are in the large lymphocyte compartment. Upon immunization these animals develop serum Id+ responses that are undistinguishable from low‐responder BALB/c mice. The relevance of these observations for the questions of physiologic self‐reactivity is discussed.
An adjunct trait of hel/i‐ab‐specific t helper cell is sensitivity to antigen‐specific immunosuppression
Authors: Araneo Barbara A. , Dowel1 Tad , Bertelsen Karin
Published: March 2007

The present study tests whether the specific inhibition of helper T (Th) cell (and T hybridomas) by suppressor T (Ts) cells is a phenotypic trait of Th cells correlating with their acquired specificity for antigedmajor histocompatibility complex or a genotypic trait not related to selection of the T cell repertoire for antigen. To do this we took advantage of the fact that H‐2d parental strains of mice commonly restrict recognition of chicken egg‐white lysozyme to the L3 peptide (a.a. 105‐129) and H‐2b parental mice to the L2 peptide (a.a. 13‐105). F1 hybrids of these strains display two subsets of lysozyme‐reactive T cells, one for each parental phenotype. Using (B10 x B10.D2)Fl mice reconstituted with B10.D2 bone marrow, we were able to develop genetic H‐2d T cell clones that could express an atypical specificity, that is L2/I‐Ab. Clones of this type, like genetic H‐2b, are also sensitive to the inhibiting effects of HEL‐activated T, cells. To overcome some of the drawbacks of using heterogeneous populations of T, B and accessory cells in our assays, we constructed T hybridomas from HEL‐immune, chimeric lymph node T cell blasts which respond to a unique antigedmajor histocompatibility complex with production of the lymphokine interleukin 2. Our results indicate that all HEL/I‐Ab‐specific T cells (helper and hybridomas) are inhibited by suppression regardless of the T cell's haplotype at the H‐2 locus: H‐2b (B10), H‐2d (D2) or H‐2b,d (BDF1). Furthermore, there is a strict correlation between the antigen and I‐A specificity: I‐Ab‐restricted T cells recognize non‐L3 determinants even though some are derived from H‐2d mice.
B cell growth and differentiation activity of interleukin‐hp1 and related murine plasmacytoma growth factors. synergy with interleukin 1
Authors: Vink Anne , Coulie Pierre G. , Wauters Pierre , Nordan Richard P. , Snick Jacques Van
Published: March 2007

It was recently shown that T cells, macrophages and fibroblasts produce growth factors for B cell hybridomas and plasmacytomas. These factors were subsequently identified as members of a new family of cytokines on the basis of NH2‐terminal amino acid sequence analyses. Using T cell‐derived interleukin‐HP1 (HP1), purified to homogeneity, as the prototype of this family, we examined the effects of these molecules in conventional polyclonal B cell activation assays with anti‐immunoglobulin antibodies or dextran sulfate as co‐stimulators.

In the absence of other cytokines, the only significant effect of HP1 was to stimulate moderately the proliferation of anti‐immunoglobulin‐activated B cells. By contrast, in conjunction with interleukin 1, HP1 became a major growth and differentiation factor not only for B cells activated with anti‐immunoglobulin antibodies but also for dextran sulfate‐stimulated and even for unstimulated B cells. In fact, with respect to cell proliferation or IgM synthesis, the IL1‐HP1 combination proved to be equivalent to B cell stimulatory factors like IL4 or IL5.

This B cell stimulatory activity was not due to the presence of a contaminant in the HP1 preparation because it was also observed with purified plasmacytoma growth factors derived from macrophages and fibroblasts, and could be inhibited by a monoclonal anti‐HP1 antibody.
Epitopes recognized by human t lymphocytes on malaria circumsporozoite protein
Authors: Sinigaglia Francesco , Guttinger Maria , Gillessen Dieter , Doran Daniel M. , Takacs BéLa , Matile Hugues , Trzeciak Arnold , Pink J. Richard
Published: March 2007

The circumsporozoite protein of the malaria parasite Plasmodium falciparum contains regions of nonrepetitive sequences which are predicted to be T cell recognition sites. We synthesized peptides corresponding to three of these regions, and tested their ability to stimulate proliferation of peripheral blood lymphocytes from donors living in a malaria‐endemic area, or from nonimmune donors. Cells from 15 out of 22 donors (including 4 of 6 nonimmune individuals) were stimulated by one or more of the peptides. T cell clones specific for one of the peptides were obtained and shown to recognize the native protein purified from sporozoites. These data help to identify T cell epitopes which could be incorporated into a malaria vaccine.
Functional evidence that intercellular adhesion molecule‐1 (icam‐1) is a ligand for lfa‐1d‐ependent adhesion in t cell‐mediated cytotoxicity
Authors: Makgoba M. William , Sanders Martin E. , Luce Gale E. Ginther , Gugel Ellen A. , Dustin Michael L. , Springer Timothy A. , Shaw Stephen
Published: March 2007

Although intercellular adhesion molecule‐1 (ICAM‐1) has been implicated as a ligand in some LFA‐1‐dependent adhesion, its importance to T cell function has not been established. The present studies investigate the importance of ICAM‐1 for human cytotoxic T lymphocytes (CTL), both in their formation of antigen‐independent conjugates (AIC) and in their lysis of targets. Analysis of monoclonal antibody (mAb) inhibition of AIC formation indicate that ICAM‐1 mAb 1 blocks (a) AIC formation with some but not all targets; (b)the LFA‐1 pathway but not the CD2LFA‐3 pathway of adhesion; (c) by binding to the target cell, not the T cell. In studies of cell‐mediated lysis (CML) ICAM‐1 mAb inhibited lysis of some targets, such as U‐937, that use ICAM‐1 predominantly in AIC formation; CML on some other targets is not inhibited by ICAM‐1 mAb. These data indicate that ICAM‐1 is a ligand for AIC formation, antigen‐specific CTL recognition and cytolysis of particular target cells. The data also indicate that ICAM‐1 is not used in LFA‐1‐dependent CTL interactions with all kinds of target cells, suggesting the existence of alternative ligands for LFA‐1.
Synergistic activation of human t cells by interleukin 1 and interleukin 6
Authors: Houssiau FrédéRic A. , Coulie Pierre G. , Olive Daniel , Snick Jacques Van
Published: March 2007

Purified human interleukin 6 (IL 6) was found to stimulate the proliferation of human tonsillar and peripheral rosetting T cells subliminally activated with phytohemagglutinin (PHA). This response seemed independent of IL2 but highly dependent on the presence of accessory cells. Indeed, when accessory cell‐depleted tonsillar T cells were activated with PHA and exposed to IL6, only minimal proliferations were observed. A similar result was obtained with IL1. However, a combination of these two cytokines induced strong proliferations, indicating that IL 1 and IL 6 play a synergistic role in the interactions between accessory cells and T lymphocytes.
The relative contributions of immune system and target organ to variation in susceptibility of rats to experimental allergic thyroiditis
Authors: Eishi Yoshinobu , Mccullagh Peter
Published: March 2007

Previous investigations of the cellular basis of genetic susceptibility to experimental allergic thyroiditis (EAT) in semi‐allogeneic mice bearing thyroid grafts from resistant, parental strain donors have indicated that these grafts remain relatively resistant to EAT when this is induced in the susceptible bearer. It was concluded that genetic control of susceptibility to EAT is expressed in both the immune system and the thyroid gland.

Our experiments in which thyroid grafts were transferred to fully allogeneic, but immunologically tolerant, recipient rats indicate that thyroid tissue from an EAT‐resistant strain of rat becomes entirely susceptible when transplanted into a susceptible host. The differing susceptibility of thyroid grafts in semi‐allogeneic and tolerant allogeneic hosts may result from restrictions on interaction between host lymphocytes and the graft in the former situation. The present findings call into serious doubt the proposition that genetically determined resistance to EAT is mediated, to any extent, at the level of the target organ.
Triggering CD 28 molecules synergize with CD 2 (T11.1 and T11,2)‐mediated T cell activation
Authors: Pierrès Anne , Lopez Marc , Cerdan Chantal , Nunes Jacques , Olive Daniel , Mawas Claude
Published: March 2007

Pairs of monoclonal antibodies (mAb) defining epitopes T11.1 and T11.2 on the CD 2 molecule are mitogenic for purified human T cells in the presence of a sub‐mitogenic dose of 12‐O‐tetradecanoylphorbol 13‐acetate (TPA). Anti‐CD 28 mAb can substitute for the action of TPA in the anti‐CD 2‐induced proliferative response of resting T cells, whereas each signal alone is unable to mediate this effect. Co‐stimulation by anti‐CD 2 plus anti‐CD 28 mAb is monocyte independent and besides resting T cells also induces strong proliferation of thymocytes and pre‐activated T cells. Modulation of the CD 3‐T cell receptor complex does not inhibit the co‐stimulatory effects of anti‐CD 2 plus anti‐CD 28 mAb. The effect is largely dependent on endogenously produced interleukin 2, since the response is strongly inhibited in the presence of mAb against the 55‐kDa interleukin 2 receptor chain.
Role of the 2H4 molecule in the activation of suppressor inducer function
Authors: Morimoto Chikao , Matsuyama Takami , Rudd Christopher E. , Forsgren Arne , Letvin Norman L. , Schlossman Stuart F.
Published: March 2007

The monoclonal antibody anti‐2H4 recognizes a 220‐kDa and 200‐kDa glycoprotein and subdivides T4+ cells into distinct subpopulations: the T4+2H4+ inducer of suppression and the T4+2H4− inducer of help. The T4+2H4+ subset has been shown to play a crucial role in the activation of T8+ suppressor cells. In the present study, we attempted to determine whether the 2H4 molecule itself may be involved in initial triggering of suppressor inducer function. The results show that the addition of anti‐2H4 antibody to a mixture of B and T cells resulted in a marked suppression of pokeweed mitogen‐driven Ig synthesis. When anti‐2H4 was added to B cell cultures containing T4+2H4+ or T4+2H4‐ cells but lacking T8 cells, no suppression was generated. In addition to the requirement for T8 cells, no suppression was generated if T4+2H4+ cells were absent. These results suggest that the anti‐2H4 antibody contributes to the activation of the T4+2H4+ lymphocyte subset, which in turn induces T8 cells to suppress B cell Ig synthesis. Biochemical analysis of the T4+2H4+ subset of lymphocytes indicated that the in vitro addition of anti‐2H4 antibody resulted in an increased expression of the 220‐kDa and 200‐kDa structure on T4 cells. We conclude that perturbation of the 2H4 molecule may potentiate the activation of the suppressor inducer subset and that the T200 molecule may be directly involved in suppressor inducer function.
The complement subcomponent C1q mediates binding of immune complexes and aggregates to endothelial cells in vitro
Authors: Daha Mohamed R. , Miltenburg André M. M. , Hiemstra Pieter S. , Klar‐Mohamad Ngaisah , Es Leendert A.Van , Hinsbergh Victor W. M.Van
Published: March 2007

The present studies were initiated to investigate whether soluble immune complexes, upon interaction with complement, can bind to endothelial cells. Human umbilical vein endothelial cells (HUVE) were incubated with purified human125I‐1abeled C1q at 4°C in RPMI‐0.5% bovine serum albumin and assayed for binding. Optimal binding of1251‐labeled C1q to HUVE was reached within 2 h, and saturation of binding was found at concentrations of 5 μg/well input. The binding of125I‐labeled C1q was inhibitable with unlabeled C1q and by the collagenous region of pepsin‐cleaved C1q. No inhibition was observed with the globular heads of C1q, suggesting that C1q binds to HUVE via the collagenous region of C1q.

When HUVE were first reacted with various concentrations of C1q, washed and subsequently incubated with125I‐labeled aggregated human IgM (AIgM), binding of125I‐labeled AIgM to HUVE occurred depending on the dose of C1q. Only those aggregates of IgM which react with C1q in a solid‐phase C1q binding assay were able to bind to HUVE presensitized with C1q. In addition it was shown that C1q mediated binding of aggregated IgG to HUVE. Furthermore, immune complexes (IC), that were prepared with bovine thyroglobulin (BTg) and rabbit anti‐BTg, bound to C1q‐preincubated HUVE. These studies suggest that localization of IC on endothelium can be enhanced following interaction of the IC with complement.
Further evidence for a sequentially ordered activation of T cell rearranging gamma genes during T lymphocyte differentiation
Authors: Triebel Frédéric , Lefranc Marie‐Paule , Hercend Thierry
Published: March 2007

Recently, we have shown that the majority of human peripheral lymphocytes with a T cell receptor (TcR) γ/δ receptor use a unique gamma chain recognized by the anti‐TigammaA monoclonal antibody. This predominantly expressed gamma protein is encoded by a rearranged gene where the V9 segment has joined the JP segment located upstream of the Cγ1 region (TRGC1). Peripheral TigammaA+ cells were further studied here to shed light on the relation between the two types of TRG rearrangements namely those involving the first (TRG1) vs. the second (TRG2) J‐C region. Thirteen clones reactive with anti‐TigammaA were tested; it was found that the second TRG allele (i.e., the one which does not involve V9‐JP) of these cells was either in germ‐line configuration or, more frequently, rearranged with a downstream V, gene joined to a J segment of the TRG1 region. These data suggest that productive rearrangements on TRG1 leading to the production of a surface‐expressed y chain occur before rearrangements involving the TRG2 region. It supports the view that TRG genes are subjected to a sequentially ordered activation during the process of T lymphocyte differentiation.
Differentiation of thymocytes in fetal organ culture: lack of evidence for the functional role of the interleukin 2 receptor expressed by prothymocytes
Authors: Plum Jean , Smedt Magda De
Published: March 2007

Thymic rudiments of 14‐day‐old mouse embryos were put into organ culture in the presence of interleukin 2 (IL2) and PC.61, a monoclonal antibody that binds to the IL2 receptor (IL2R). After 5 and 7 days of culture, we found no influence of PC.61 on the growth of the thymus and the composition of the thymocyte subpopulations as studied with a panel of monoclonal antibodies. High‐dose IL 2 treatment of the organ culture resulted in a reduction of the number of thymocytes and a decrease in the single CD4+ and CD4+CD8+ thymocytes, whereas the number of CD8+Ly‐1+ thymocytes and the number of CD4−CD8−Ly−1− IL2R+ thymocytes increased. The effect of high‐dose IL2 treatment was ascribed to the induction of a nonspecific LAK activity. Our findings argue against a functional role of IL2R on prothymocytes during early T cell development.
The progression of the inflammation in established collagen‐induced arthritis can be altered by treatments with immunological or pharmacological agents which inhibit T cell activities
Authors: Hom Joanne T. , Butler Larry D. , Riedl Pamela E. , Bendele Alison M.
Published: March 2007

Alterations in the progression of the inflammatory disease in mice with established collagen‐induced arthritis (CIA) by in vivo treatments with either anti‐T cell antibodies or an immunosuppressive drug, whose main targets of action are T cells, were studied. It was demonstrated that the in vivo administration of either monoclonal anti‐L3T4, anti‐Ly‐2 or the combination of anti‐L3T4 and anti‐Ly‐2 failed to modify the inflammatory disease after the arthritis had been initiated. Nevertheless, the progression of disease was decreased by treatments with rabbit anti‐mouse lymphocyte sera (ALS) in mice with established CIA. While there was a substantial reduction in the proliferative responses to the T cell mitogen concanavalin A (Con A) in these ALS‐treated mice, proliferation to a B cell mitogen, lipopolysaccharide, was unaffected. Furthermore, treatments with anti‐Thy‐1.2 monoclonal antibody (mAb) by itself did not alter the progression of the ongoing inflammatory disease, but combined treatments with both anti‐Thy‐1.2 and anti‐L3T4 mAb prevented the further advancement of the arthritic disease. Although mice receiving either anti‐Thy‐1.2 alone or both anti‐Thy‐1.2 and anti‐L3T4 exhibited complete absence of Thy‐1+ cells within their inguinal lymph nodes, the proliferative responses to Con A by LN cells from mice treated with the combination of anti‐Thy‐1.2 and anti‐L3T4 were drastically reduced compared to the responses of either the anti‐Thy‐1.2 or anti‐13T4‐treated groups. Finally, daily treatments with cyclosporin A, an immunosuppressive drug which preferentially acts on T cells, were also effective in modifying the clinical course of the arthritic disease in mice with established CIA. These results suggest that immunocompetent cells which express the Thy‐1 surface marker, most likely Thy‐1+ T cells, may play a role in maintaining and perpetuating the inflammatory disease of established CIA.
Immunoglobulin synthesis in the human myeloma cell line U‐266; expression of two immunoglobulin heavy chain isotypes (ϵ and α) after long‐term cultivation in vitro
Authors: Hellman Lars , Josephson Staffan , Jernberg Helena , Nilsson Kenneth , Pettersson Uif
Published: March 2007

A human IgE‐producing myeloma has been cultivated in vitro as a continuous cell line (U‐266) since 1968. Analysis of immunoglobulin production during early passages of the cell line demonstrated a high synthesis rate of monoclonal IgE. Analysis of late passages, cultivated after 1980, revealed a 3‐6‐fold lower rate of IgE secretion, This decrease was accompanied by the appearance of small amounts of IgA in the culture medium together with IgE. RNA was extracted from a late passage of U‐266 and analyzed by Northern blotting, using ϵ and α‐specific oligonucleotides as hybridization probes. The results showed the presence of ϵ as well as α‐specific mRNA. Moreover the results demonstrated that the latter mRNA was derived from the α2 locus and that the ϵ and the α2‐specific mRNA contained the same V region sequences. Southern blot analysis of DNA from the late passage of the U‐266 cell line failed to reveal a recombinatory switch from the ϵ locus to the α2 locus. The expression of α2 is thus likely to be caused by differential splicing rather than by an isotype switch at the DNA level.
Uptake of extracellular Ca2+ and not recruitment from internal stores is essential for T lymphocyte proliferation
Authors: Gelfand Erwin W. , Cheung Roy K. , Mills Gordon B. , Grinstein Sergio
Published: March 2007

Changes in free cytosolic calcium concentrations ([Ca2+]i]are thought to be important initiating events in the activation of T lymphocytes. Mitogen‐induced increases in [Ca2+Ii may result from net influx across the plasma membrane and/or release of Ca2+ from intracellular stores. In human T lymphocytes loaded with the fluorescent indicator indo‐1, addition of phytohemagglutinin (PHA) or the anti‐CD3 antibody UCHT‐1 elicits a biphasic [Ca2+]i response. A major component of the initial transient peak was due to release from internal stores whereas the lower plateau phase was sustained by Ca2+ influx. Previous work suggested that Ca2+ influx is essential for interleukin 2 (IL2) secretion and cell proliferation. To determine the relative effects of the initial and sustained phases of [Ca2+]i change, IL2 secretion and cell proliferation, we introduced into the cell 1, 2‐bis(o‐aminophenoxy)ethane‐N,N,N′,N′‐tet‐raacetic acid (BAFTA), a high affinity intracellular Ca2+ chelator which neither contributes to nor interferes with the fluorescence determinations of [Ca2+]i In cells preloaded with BAPTA, both PHA and UCHT‐1 antibody failed to elicit the transient [Ca2+]i overshoot. Only the plateau phase could be observed in the presence of extracellular Ca2+. In contrast, BAPTA‐loaded cells were found to be fully functional when assessed for IL2 receptor expression, IL2 secretion and cell proliferation. Thus, the mitogen‐induced, maximal but transient increase in [Ca2+]i, contributed to mainly by release of Ca2+ from internal stores, does not appear to be essential for these T cell responses.
Interleukin 5 enhances interleukin 4‐induced IgE production by normal human B cells. The role of soluble CD23 antigen
Authors: Pène Jérǒme , Rousset Françoise , Brière Francine , Chrétien Isabelle , Wideman Janus , Bonnefoy Jean Yves , Vries Jan E.De
Published: March 2007

Interleukin 4 (IL 4)‐induced IgE production by peripheral blood lymphocytes and tonsil cells from normal donors was enhanced in a dose‐dependent fashion by IL5. IL5 tested alone was not effective. The synergistic effects of IL5 were most pronounced at suboptimal IL4 concentrations, whereas at saturating IL4 concentrations (200‐300 U/ml), IL5 had no effect. Interferon‐γ (IFN‐γ) and F(ab′)2 fragments of monoclonal antibody 25 directed against the CD23 antigen, that blocked IL4‐induced IgE synthesis, also inhibited the production of IgE in the presence of combinations of IL4 and IL5, indicating that IL5 potentiates the activation pathway through which IL4 induces IgE production. In contrast, IL4 (50 U/ml) blocked IL5‐induced IgA synthesis. IL 5 was ineffective in inducing the release of soluble CD23 (sCD23), but in the presence of IL4 an enhanced release of sCD23 was observed, provided IL4 was present at suboptimal concentrations. IFN‐γ completely blocked sCD23 release induced by IL4 and IL5. These results demonstrate that there is a strong quantitative correlation between sCD23 release and induction of IgE synthesis. sCD23 fractionated from the Epstein‐Barr virus‐transformed B cell line RPMI 8866 was ineffective in inducing IgE production. However, sCD23 acted synergistically with suboptimal concentrations of IL4. sCD23 did not modulate the IgE response at saturating concentrations of IL4. Collectively, these data indicate that sCD23 plays an important regulatory role in the modulation of IL4‐induced IgE synthesis mediated by IFN‐y and IL5.
Ly‐6 A/E antigen of murine T cells is associated with a distinct pathway of activation. Requirements for interferon and exogenous interleukin 2
Authors: Toulon Maureen , Palfree Roger G. E. , Palfree Susan , Dumont Francis J. , Hämmerling Ulrich
Published: March 2007

The Ly‐6 pathway of T cell activation was analyzed to identify its essential requirements. Using a monospecific chicken antiserum to Ly‐6E, fully cross‐reactive to its allelic counterpart, Ly‐6A, but unreactive with other members of the Ly‐6 family, we have found that interferon (IFN)‐α/β or γ, Ly‐6 antibody and interleukin 2 (IL2) act synergistically in inducing T cell proliferation. The action of IFN can be attributed to induction of Ly‐6 A/E antigen on T cells, as described previously, and this induction is transcriptionally controlled. Exposure of T cells with elevated Ly‐6 concentrations to chicken anti‐Ly‐6 antibody leads to expression of IL2 receptors. Consequently, the addition of IL2 drives T cell proliferation. Thus, in BALB/c mice the minimum requirements for activation by the Ly‐6 pathway are IFN (as a means of inducing Ly‐6), Ly‐6 antibody (as inducer of IL2 receptors) and IL2. In mice of the Ly‐6. 2 haplotype, IFN is not an absolute requirement. This may be related to the fact that these animals, in contrast to those of Ly‐6.1 haplotype, express Ly‐6 constitutively on a substantial proportion of resting T cells. Thus, T cells of C57BL/6 or DBA/2 mice can be induced to proliferate with Ly‐6 antibody and IL2 alone, although IFN pre‐treatment enhances this response. In BALBic mice the IL2‐driven proliferative response induced through the Ly‐6 pathway occurs selectively in the L3T4− population.
Immunoglobulin diversification in embryonic chicken bursae and in individual bursal follicles
Authors: Lassila Olli , Alanen Anna , Lefkovits Ivan , Cooper Max D. , Pink J.Richard
Published: March 2007

Previous studies have shown that the same immunoglobulin (Ig) Vλ gene (Vλ 1) is rearranged in all chicken B cells, and that extensive sequence diversification of this gene occurs during B cell development in the bursa of Fabricius. We used two‐dimensional gel electrophoresis to compare the heterogeneity of Ig λ light chains produced by B cells at different stages of bursal development. Somatically diversified light chains were observed in Ig molecules produced by bursal cells as early as 15 days of embryonic incubation. The two principal species of light chain observed probably represent glycosylated and nonglycosylated forms of λ chain encoded by alleles of a single λ gene. Extensive diversification was observed during late embryogenesis. We also studied λ light chain diversity in cyclophosphamide‐treated birds repopulated with normal bursal cells. In these birds, individual bursal follicles are repopulated by single B cell precursors. Follicular cells derived from single B cell precursors were able to produce a spectrum of light chains almost as diverse as that of the total bursal cell population. We used two monoclonal anti‐idiotype antibodies to study idiotype expression in individual normal or reconstituted follicles. About 30% of follicles contained 0.1% to 5% of lymphocytes which reacted with one or both of the antibodies. The results indicate that within individual bursal follicles bursa stem cells undergo Ig hyperdiversification.
Establishment of an interleukin 6 (IL 6)/B cell stimulatory factor 2‐dependent cell line and preparation of anti‐IL 6 monoclonal antibodies
Authors: Matsuda Tadashi , And Toshio Hirano , Kishimoto Tadamitsu
Published: March 2007

Murine hybridomas producing monoclonal antibodies (mAb) specific to human interleukin 6 (IL6/BSF‐2) were established. One of these hybridomas (MH60.BSF2) was found to be dependent on IL6 for its in vitro growth. None of the known biological factors tested, such as recombinant (r) human (Hu) Illα, rHuILlα, rHuIL2, rHuIL3, rHuIL4, rHu interferon (1FN)‐γ, HuIFN‐β, rHuG‐CSF, or recombinant murine (Mu) IL3, MuIL4, rMuIL5, could induce the in vitro growth of MH60.BSF2 cells. The half‐maximum tritiated thymidine uptake by MH60.BSF2 cells could be achieved by picogram amounts of rIL 6, making this hybridoma clone an indicator cell for specific and sensitive detection of the IL6 activity in test samples. The MH166.BSF2 clone was found to produce IgGl,χ type mAb (αBSF2‐166) capable of neutralizing IL6 activity. The other clone, MH60.BSF2, produced IgM,x type mAb (aBSF2‐60) unable to neutralize IL6 activity. Both mAb specifically reacted with IL6 as demonstrated by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and Western blotting analysis. An enzyme‐linked immunosorbent assay (ELISA) utilizing αBSF2‐166 and rabbit anti‐IL 6 antibodies was established which could detect as low as 50 pg/ml of IL6. Since both the ELISA and MH60.BSF2 hybridoma could detect small amounts of IL6 in biological fluids, they constitute powerful tools in exploring the presence or the role of IL6 in various immunological disorders.
Interleukin 6 is involved in interleukin 1‐induced activities
Authors: Helle Maarten , Brakenhoff Just P. J. , Groot Els R.De , Aarden Lucien A.
Published: March 2007

Human monocytes produce a number of soluble mediators involved in regulation of inflammation and lymphocyte growth and differentiation such as interleukin 1 (IL1) and tumor necrosis factor. Recently, the cDNA of another monocyte‐derived factor, interleukin 6 (IL6), was cloned. Herein we show that purified E. coli‐derived recombinant IL6 (rIL6) is as active as IL 1 in the thymocyte assay. In addition, IL 1 and IL 6 synergize strongly in stimulating thymocyte proliferation. Another property shared by IL 1 and IL6 is their pyrogenicity. Human rIL6 induces a monophasic fever after i.v. injection into rabbits. Together with the observation that IL 1 induces IL6 in a variety of cells including thymocytes, our data suggest that IL6 is involved in many of the pleiotropic effects of IL1.
Induction of T cell receptor γ chain transcription in murine T cells by trans‐complementation
Authors: Marolleau Jean‐Pierre , Cazenave Pierre‐André , Primi Daniele
Published: March 2007

As an initial approach to understanding the molecular basis of the developmentally regulated expression of T cell receptor (TcR) genes, we constructed hybrids among T cell clones that differ in their expression of CD4 and CD8 antigens as well as in α,β and γmRNA levels. Here we report that the TcRγ gene becomes transcriptionally active in hybrid cells formed between parental clones that lack TcR γ mRNA. We also observed negative trans‐regulation of TcR β but not of TcR α transcription in one of these hybrids. Positive TcR γ transcription was observed both with (CD4−CD8− × CD4−CD8‐) and (CD4−CD8− × CD4+CD8+) hybrids while negative TcRβ gene regulation was only detected in (CD4−TD8‐ × CD4+CD8+) cells. These data suggest that the regulation of TcR α, β and γ genes is mediated by the action of specific transacting factors that become asynchronously active in the various stages of T cell development.
Development of autoreactive L3T4+ T cells from double‐negative (L3T4−/Ly‐2−) Thy‐1+ spleen cells of normal mice
Authors: Reimann JÖRg , Bellan Astrid , Conradt Peter
Published: March 2007

Thy‐l+/L3T4−/Ly‐2− spleen cells were purified from normal C57BL/6 (B6) and C.B‐17 mice. Cells within this subset expressed the T cell receptor (TcR) for antigen: the majority of cells in this subset were CD3+; a fraction of the cells was stained with the monoclonal antibody (mAb) F23.1; and the TcR molecule was immunoprecipitable with mAb F23.1 from cells within this subset. In limiting dilution analyses, about 1/30 cells within this subset were growth inducible in vitro by stimulation with phorbol myristate acetate (PMA) plus ionomycin; conditioned media containing interleukin (IL)1, IL2, IL3 or IL4 activity neither triggered nor promoted in vitro growth of these cells. The in vitro generated T cells displayed the Thy‐l+/L3T4+/Ly‐2− surface phenotype and were self‐reactive, i.e., proliferated preferentially in response to syngeneic stimulator cells, and secreted IL2 and IL3 only in response to syngeneic but not allogeneic stimulator cells. The proliferative response of these cells to syngeneic stimulator cells was blocked by anti‐self Ia mAb. This autoreactive helper T cell subset was not inducible in purified Thy‐1+ spleen cell subsets from athymic nude mice or scid mice. Autoreactive helper T cells did not express detectable levels of the IL2 receptor (IL2R), and their proliferative response was not blocked by anti‐IL2R mAb. From PMA plus ionomycin‐stimulated double‐negative Thy‐l+ spleen cells, 14 T cell clones were established in long‐term culture which displayed the CD3+CD4+CD8− surface phenotype and were self‐reactive.
On the structure of polymeric IgM
Authors: Davis Ann C. , Roux Kenneth H. , Shulman Marc J.
Published: March 2007

The cysteine at position 575 of the immunoglobulin μ heavy chain is thought to provide the only disulfide bonds joining the monomer subunits of mouse polymeric IgM. The importance of this cysteine in the assembly of polymeric IgM was investigated by using site‐directed mutagenesis to produce μ chains with serine at position 575. Thirty percent of the secreted mutant IgM was covalently assembled polymer implying that cysteines other than Cys575 can form inter‐subunit disulfide bonds. The polymeric IgM lacked J chain, mediated complement‐dependent cytolysis and appeared to have a higher molecular weight than conventional IgM pentamers, as judged by sucrose gradient sedimentation and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis mobility. Electron microscopy revealed that the mutant IgM molecule contained six subunits.

Wild‐type IgM, while synthesized predominantly as a pentameric molecule, was assembled in at least two other forms, which were distinguished by their electrophoretic mobility. The apparently higher molecular weight forms of wild‐type IgM include hexameric molecules which, like the hexameric mutant IgM, contained much less J chain that the pentameric form and were 20‐fold more efficient at activating complement‐dependent cytolysis.
B cell participation in the recursive selection of T cell repertoires
Authors: Marcos Miguel Angel R. , De La Hera Antóio , Pereira Pablo , Marquez Carlos , Toribio Marisa , Coutinho António , Martinez‐A. Carlos
Published: March 2007

Normal BALB/c mice produce 2,4,6‐trinitrophenyl (TNP)‐I‐Ad specific T helper (Th) cells expressing a receptor heterodimer which share with anti‐TNP antibodies an idiotope defined by the F6(51) anti‐idiotypic antibody. Expression of this Th idiotype is controlled by major histocompatibility complex and immunoglobulin heavy chain‐linked genes and results from antibody‐dependent selection of T cell repertoires (Martinez‐A. et al., Eur. J. Immunol. 1986. 16: 417). We now present evidence for the recursive nature of T → B cell repertoire selection and suggest that perinatal B cells, present in adult peritoneal cavity, operate in the early phases of this process. Thus, the Th idiotype is absent in BALB/c mice which are either suppressed from birth with anti‐p antibodies, or reconstituted with autologous bone marrow after lethal irradiation as adults. Supplementation of bone marrow reconstitution with syngeneic Thy‐1−, Ly‐1+ peritoneal B cells, however, selects Th cell repertoires that are undistinguishable from normal mice as to expression of the F6 (51) clonotype. This effect is lost after depletion of Ly‐1− cells in the reconstituting Thy‐1− peritoneal cell population. Interestingly, large in vivo “naturally” activated Ly‐1− splenic B cells can also reconstitute Th idiotype expression if they .are isolated from normal, but not from athymic, nude donors. However, transfer of normal large splenic T cells to adult nude mice “educates” the splenic “large B cell” compartment in these animals such that they acquire the ability to recursively select, upon transfer to bone marrow reconstituted recipients, the Th clonotype. Small resting lymphocytes in either the B or T cell lineage fail to exert these selective effects. These observations constitute formal evidence for recursive repertoire selection in the naturally activated lymphocyte compartment of normal animals.
The human intermediate‐affinity interleukin 2 receptor consists of two distinct, partially homologous glycoproteins
Authors: Herrmann Thomas , Diamantstein Tibor
Published: March 2007

In this report we demonstrate that the human intermediate‐affinity‐type interleukin (IL)2 receptor (IL2R) consists of two distinct glycoproteins designated H1 and H2, whereas the high‐affinity IL2R consists of three chains, H1, H2 and the light chain (L), the Tac antigen. They are neither linked by disulfide bridges to each other nor to the L chain. Similar to the L chain, H1 and H2 apparently carry intramolecular disulfide bonds. From affinity‐labeled IL2 intermediate‐affinity receptor complexes, we deduced an apparent mol. mass of 70 kDa for H1 and of 75 kDa for H2 in sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) and of 55 kDa for H1 and of 85 kDa for H2 in SDS‐PAGE/urea. As demonstrated by limiting proteolysis, both glycoproteins display high homologies or even identity proximal to the IL2‐binding sites. The areas which are responsible for the striking differences between H1 and H2 in SDS‐PAGE/urea are located distally to the IL2‐binding site and, in contrast to the L chain, are protected from the action of exogenous proteases by the plasma membrane.
Mechanisms of monoclonal antibody‐facilitated tolerance induction: a possible role for the CD4 (L3T4) and CD11a (LFA‐1) molecules in self‐non‐self discrimination
Authors: Benjamin Richard J. , Qin Shixin , Wise Matthew P. , Cobbold Stephen P. , Waldmann Herman
Published: March 2007

In vivo therapy with a CD4 (L3T4) monoclonal antibody is able to provide a tolerogenic milieu for a limited number of protein antigens. In this study we have analyzed the mechanisms of such tolerance to human gamma globulin, and show that tolerance is induced in adult T helper cells without a need for cellular depletion, and that it is probably not maintained by suppressor mechanisms nor by regulatory cellular circuits involving CD8+ (Ly‐2+) cells. Tolerance induction is not a property peculiar to the CD4 molecule, as similar effects can be elicited with a monoclonal antibody directed to the CD11a (LFA‐1) molecule. We suggest that tolerance is maintained by the functional deletion of mature T helper cells and that adhesion molecules, such as CD4, CD8 and CD11a, may play a critical role in T cell discernment of self from non‐self.
Genetic restriction of the murine humoral response to a recombinant Plasmodium vivax circumsporozoite protein
Authors: Nardin Elizabeth H. , Barr Philip J. , Heimer Edgar , Etlinger Howard M.
Published: March 2007

The antibody response of inbred and congenic strains of mice immunized with a recombinant Plasmodium vivax circumsporozoite protein was investigated. Only mice of the H‐2k and H‐2a haplotypes developed antibodies that react with P. vivax sporozoite in an indirect immunofluorescence assay and with the recombinant protein in enzyme‐linked immunosorbent assay. Congenic recombinant strains were used to map Ir gene control to the I‐Ak locus. A similar pattern of genetic restriction was found when congenic strains were immunized with a carrier‐free synthetic peptide corresponding to the repeat region of the P. vivax circumsporozoite protein. The results suggest that the ability of T helper cells to recognize a T cell epitope(s) in the repeat region of the P. vivax circumsporozoite protein is genetically restricted.
The double reactivity of a human monoclonal rheumatoid factor to IgG and histones is related to distinct binding sites
Authors: Pasquali Jean Louis , Azerad Graziella , Martin Thierry , Muller Sylviane
Published: March 2007

The structural basis of the double reactivity of a human monoclonal rheumatoid factor (RF) with both human IgG and histones H1 and H3 was investigated by means of competitive inhibition experiments. The monoclonal RF binding to solid‐phase histones was inhibited by increasing concentrations of heat‐aggregated IgG. However, increasing concentrations of purified histones were almost unable to reduce the RF binding to solid‐phase IgG. Inhibition of antigen binding with two murine monoclonal anti‐idiotopes reacting with distinct idiotopes on the monoclonal RF indicated that the fixation to the different antigens was mediated by distinct binding sites. This result was confirmed by showing the selective sensitivity to mild acid treatment of the histone binding site but not of the IgG binding site. This report provides a structural basis for the existence of polyfunctional combining regions on a human autoantibody.
Co‐expression of Mac‐1 and p150,95 on CD5+ B cells. Structural and functional characterization in a human chronic lymphocytic leukemia
Authors: Hera Antonio De La , Alvarez‐Mon Melchor , Sanchez‐Madrid Francisco , Martinez‐A Carlos , Durantez Alberta
Published: March 2007

The leukocyte adhesion receptors (LAR) Mac‐1 and p150,95 were thought to occur only on myeloid cells, but recently, mouse Ly‐1+ (CD5+) B and pro‐B cells were shown to bind M1/70 monoclonal antibody, an anti‐Mac‐1 antibody. Using immuno‐precipitation, sodium dodecyl sulfate gel electrophoresis, immunofluorescence and flow cytometry, we have studied the expression of LAR in human CD5+ B cells from chronic lymphocytic leukemia (B‐CLL) patients. 170,95 kDa Mac‐1 and p150,95, as well as 180,95 kDa LFA‐1 heterodimers are shown to be co‐expressed on CD5+μ+μ+ B cells from a patient where they retain their known function in homotypic cell‐cell adhesion. Therefore, functional Mac‐1 and p150,95 LAR are not restricted to myeloid cells.