bluuebunny/crossref_metadata_2025 huggingface dataset:
A private idiotype can become recurrent through genetic recombination and gene(s) unlinked to the Igh locus governs its expression
Authors: Mertens Frederic , Berek Claudia , Andris Fabienne , Willems Fabienne , Brait Maryse , Miller Robert , Riblet Roy J. , Slaoui Moncef , Urbain Jacques
Published: March 2007

Any immune response is characterized by its idiotypic profile. Two different kinds of idiotype (Id) have been described. Private Id are restricted to a few individuals from a species while recurrent Id appear in a large majority of individuals from the same species immunized with the same antigen. We describe, in this report, an experimental model whereby a private Id can become recurrent through genetic recombination. The immune response of A mice against the hapten arsonate is characterized by a recurrent Id called cross‐reactive idiotype A (CRIA). A strongly CRI, called CRIA‐like, can be occasionally detected in some BALB/c mice (5% to 10%) immunized with arsonate. Molecular studies show that CRIA and CRIA‐like antibodies have highly homologous D segments and identical light chains. By contrast, their VH segments are vastly dissimilar. We have examined the anti‐arsonate response of inbred strains of mice whose Igh loci are recombinant between those of A/He and BALB/c. Interestingly, we have observed that the CRIA‐like Id which is private in BALB/c becomes recurrent in the AXC‐1 strain which harbors the VH genes from BALB/c, the DH and CH genes from A/He. Structural studies demonstrate that highly homologous, VH, VL and D segments are used in BALB/c and AXC‐1mice. The basis for this differential expression of highly similar genes could be linked to the DH locus. However, F1 mice stemming from the cross between AXC‐1 and BALB/c do not express the Id. The backcross analysis shows that the non‐expression of the Id in F1 mice depends on genes unlinked to the Igh locus.
Control of primary and secondary antibody responses by cytotoxic T lymphocytes specific for a soluble antigen
Authors: Yefenof Eitan , Zehavi‐Feferman Revital , Guy Rina
Published: March 2007

BALB/c mice immunized with keyhole limpet hemocyanin (KLH) develop Thy‐1+ and CD8+, KLH‐specific cytotoxic T cells (Tc). Such Tc cells can lyse TNP‐specific B cells activated with TNP‐KLH, but not with TNP‐ovalbumin. Cytotoxicity was inhibited by anti‐H‐2K/D antibodies, but not by anti‐Ia antibodies, suggesting a major histocompatibility complex class I‐restricted killing. Selective enrichment for virgin and memory TNP‐specific B cells revealed that the latter cells were relatively resistant to lysis by KLH‐specific Tc cells. Depletion of CD8+ T cells from cultures of TNP‐specific virgin B cells activated with TNP‐KLH and KLH‐primed T cells, increased the titer of anti‐TNP antibodies in the culture supernatants. This increase was reduced if KLH‐primed CD8+ T cells were added to the culture 1 day before its termination. Anti‐TNP antibody secretion by memory B cells activated in the same manner was not affected by depletion or addition of CD8+ cells. These results suggest that Tc cells are generated following immunization with a soluble antigen which may participate in the down‐regulation of primary B cell responses.
Antigens recognized on a melanoma cell line by autologous cytolytic T lymphocytes are also expressed on freshly collected tumor cells
Authors: Degiovanni Gérard , Hainaut Philippe , Lahaye Thierry , Weynants Patrick , Boon Thierry
Published: March 2007

Peripheral blood lymphocytes of a melanoma patient were stimulated in vitro with a permanent cell line derived from the autologous tumor. Stable cytolytic T lymphocyte (CTL) clones were obtained that lysed the melanoma cell line and did not lyse autologous Epstein‐Barr virus‐transformed B lymphocytes or K‐562 cells. These CTL clones were directed against two distinct antigens on the melanoma line. In view of the possibility that these antigens could be culture artefacts, we tested the stimulatory ability of tumor cells that had been freshly collected from metastatic relapses on the CTL clones. A considerable CTL proliferation was observed and it appeared to be specific. We conclude that the antigens recognized by the autologous CTL clones on the permanent melanoma cell line were expressed by the tumor cells in the patient.
Quantitative changes in T cell DNA methylation occur during differentiation and ageing
Authors: Golbus Joseph , Palella Thomas D. , Richardson Bruce C.
Published: March 2007

DNA methylation is one of the mechanisms involved in the regulation of developmentally relevant genes. Previous experiments demonstrated that T cells treated with DNA methylation inhibitors reacquire some of the phenotypic and functional characteristics of thymocytes, suggesting that DNA methylation may be involved in regulating some of the changes in gene expression during thymic maturation. To further examine whether changes in DNA methylation occur during T cell differentiation, total DNA deoxymethylcytosine content was compared in human thymocyte subsets and mature T cells. A significant increase in deoxymethylcytosine was found at the end of T cell differentiation which then decreased with age. These results suggest that increased DNA methylation may serve to silence genes following T cell differentiation. The results also raise the possibility that age‐related decreases in T cell DNA methylation may contribute to changes in T cell function occurring in the elderly.
Human breast milk T lymphocytes display the phenotype and functional characteristics of memory T cells
Authors: Bertotto Alberto , Gerli Roberto , Fabietti Giulio , Crupi Silvana , Arcangeli Carla , Scalise Francesco , Vaccaro Renato
Published: March 2007

Naive (unsensitized) and memory (antigen‐primed) T cells can be phenotypically distinguished on the basis of the high or low intensity with which they express a number of immunologically relevant lymphocyte membrane antigens, including CD45R, CDw29, UCHL1, LFA‐1, LFA‐3, CD2 and Pgp‐1. Here we report that in contrast to the two major T cell subsets found in the blood, milk T lymphocytes are almost exclusively composed of the one which exhibits the CD45Rlow, CDw29, UCHL1, LFA‐1high memory T cell phenotype. In addition, while milk and autologous blood cells expressed similar levels of CD3 surface antigens, CD2 and ICAM‐1 expression was approximately twofold greater on the milk T lymphocytes. This agrees with the finding that whereas colostrum T cells respond poorly to PHA, they proliferate and produce interferon‐γ normally when stimulated with either the anti‐CD3 or anti‐CD2 monoclonal antibodies. The selective colonization of the mammary gland during lactation by a population of T lymphocytes which displays the phenotype and functional characteristics of memory T cells may be one of the mechanisms whereby the suckling infant benefits from its mother's immunological experience.
Antigen presentation by keratinocytes induces tolerance in human T cells
Authors: Bal Vineeta , McIndoe Angus , Denton Graeme , Hudson David , Lombardi Giovanna , Lamb Jonathan , Lechler Robert
Published: March 2007

Antigen recognition by interleukin 2 (IL 2)‐producing T lymphocytes can lead to two distinct outcomes, depending on the nature of the antigen‐presenting cell. Recognition of antigen presented by specialized antigen‐presenting cells leads to T cell activation; in contrast, antigen presentation by cells which lack “accessory function” can lead to a state of specific nonresponsiveness, which is characterized by a failure to produce IL 2. We have shown in this study that co‐culture of an HLA‐DR1/4‐restricted, influenza hemagglutinin‐specific T cell clone with a specific peptide presented by interferon‐γ‐induced DR4‐expressing keratinocytes causes tolerance induction. This effect was DR restricted, in that it required pre‐incubation of the T cell clone with keratinocytes expressing an appropriate DR type (DR 4 Dw14). The induction of T cell tolerance was also antigen specific; no inhibition resulted from pre‐incubation of the clone with an irrelevant peptide. Furthermore cell to cell contact appeared to be necessary, and the addition of supernatant from interferon‐γ‐induced keratinocytes did not cause any inhibition. This phenomenon may have relevance to the immunogenicity of transplanted cultured keratinocytes and to the effects of major histocompatibility complex class II induction on non‐bone marrow‐derived cells. Presentation of tissue‐specific autoantigens by cells such as keratinocytes may provide a mechanism of avoiding, rather than stimulating, autoimmune reactions in the context of a local inflammatory response.
Immunoglobulin light chain transcripts with altered V regions in Burkitt's lymphoma cell lines producing short μ chains
Authors: Cogné Michel , Mounir Samir , Aucouturier Pierre , Preud'homme Jean‐Louis , Nau François , Guglielmi Paul
Published: March 2007

The Burkitt lymphoma cell lines Ly91, Ly47 and Ly66 produce short μ chains in the absence of associated light (L) chains. μ mRNA lack two‐thirds of the variable (V) region due to an alternate splicing event that takes place within V genes. L chain genes were found to be rearranged in these lines and to lead to transcripts with altered V regions. Although these abnormal transcripts displayed specific abnormalities in each cell line, they shared some features, including large deletions involving the V‐J junction. In one cell line, L chain transcripts made up of either VxI subgroup gene Jx3 or VxIV gene‐Jx4 recombination products bore a similar alteration: the donor splice site of the rearranged Jx segment was modified, leading to the alternate use of the donor site of either the leader peptide exon or the next 3′ unrearranged Jx segment.
Binding of toxic shock syndrome toxin‐1 to murine major histocompatibility complex class II molecules
Authors: Scholl Paul R. , Sekaly Rafick‐P. , Diez Ana , Glimcher Laurie H. , Geha Raif S.
Published: March 2007

The staphylococcal exotoxin toxic shock syndrome toxin‐1 (TSST‐1) has potent stimulatory effects on murine and human lymphocytes. This is the consequence of TSST‐1 binding to major histocompatibility complex (MHC) class II molecules and the engagement in a Vβ‐restricted fashion of the T cell receptor by the TSST‐1‐MHC class II complex. Using radioligand and functional assays we have recently shown that TSST‐1 binds to all HLA‐DR (n = 14), HLA‐DQ (n = 2) and HLA‐DP (n = 2) phenotypes tested. In this study, we have examined the ability of murine MHC class II molecules to bind TSST‐1. Specific high‐affinity binding of TSST‐1 was detectable to unfractionated BALB‐c (H‐2d) and C57BL/6 (H‐2b), but not to C3H (H‐2k) spleen cells. The Kd of this binding estimated from Scatchard analysis was in the same nanomolar range as the Kd of binding of TSST‐1 to HLA‐DR. Binding of 125I‐labeled TSST‐1 to BALB/c‐derived B cell lymphoma lines and to L cell transfectants correlated with the expression of I‐A molecules, but not with the expression of I‐E molecules. Furthermore, I‐A+, I‐E− cells but not I‐A−, I‐E+ cells were able to support TSST‐1‐induced T cell proliferation. The binding affinity of TSST‐1 for I‐Ak appears to be much lower than for I‐Ad. L cell transfectants expressing hybrid DRα: I‐E molecules, but not those expressing I‐E: DR1β molecules, could bind TSST‐1 and efficiently support TSST‐1‐induced T cell proliferation. This suggests that minor differences in the highly homologous I‐Eα and DRα chains are critical in determining the affinity of the MHC class II molecule for TSST‐1. These results demonstrate that the binding of TSST‐1 to MHC class II molecules in the mouse, in contrast to humans, is strongly influenced by phenotype. Analysis of the molecular basis of these differences may help to localize staphylococcal exotoxin binding sites on MHC class II molecules.
Characterization of the interleukin 5‐reactive splenic B cell population
Authors: Rolink Antonius G. , Thalmann Philipp , Kikuchi Yuji , Erdei Anna
Published: March 2007

The characteristics of the interleukin (IL) 5‐reactive splenic B cell population of C57BL/6 nu/nu mice, with respect to IL5/IL2 reactivity, cell surface phenotype, VH gene family usage, autoreactivity and the structure of the IL5 receptor (IL 5R), were analyzed.

It was found that 2%–4% of splenic B cells express relatively high levels of IL 5R as determined by the binding of the anti‐IL 5R monoclonal antibody R52.120. Over 90% of the splenic B cells that mature to IgM secretion upon activation with IL5 are comprised in this small subpopulation of B cells. Moreover, the vast majority of splenic B cells that mature to IgM‐secreting cells when activated by IL2 also reside in this IL 5R+ B cell population. The cell surface phenotype of the IL 5R+ splenic B cells is IgM+, B220+, Ly‐1− and IL 2R p55−. Upon activation with IL 5 this cell surface phenotype changes, in that a vast majority of the B cells then express the p55 chain of the IL 2R, whereas the level of IL 5R decreases. VH gene family usage in the IL5‐activated splenic B cells was analyzed by in situ hybridization. VH gene family usage was found to be random and not different from the VH genes expressed in LPS‐activated B cells.

Hybridoma collections from IL5‐activated splenic B cells and LPS‐activated B cells were screened and compared for the production of autoantibodies and antibodies directed against the haptens (4‐hydroxy‐3‐iodo‐5‐nitrophenyl)acetyl (NIP) and 2,4,6‐trinitrophenyl (TNP). In both collections high, but not significantly different frequencies of autoantibody‐(32% IL5, 31.4% LPS) and of anti‐hapten antibody (27.8% IL5, 18.6% LPS)‐producing hybridomas were found.

The structure of the IL 5R on IL5‐activated B cells was analyzed by 125I‐labeled IL5 binding and cross‐linking. About 100 high‐affinity (10−11 M) and 1000 low‐affinity M IL5‐binding sites are present on IL5‐activated splenic B cells, and both high‐ and low‐affinity IL 5R are similar to those expressed on the IL5‐dependent B13 cell line. Cross‐linking of 125I‐labeled IL5 to the receptors on IL5‐activated B cells revealed one major IL5‐binding protein of 45–50 kDa molecular mass and another minor binding protein of 130–140 kDa. The same IL5‐binding proteins are present on the IL5‐dependent B13 cell line. Thus, we conclude that the structure of the IL 5R on splenic B cells is identical to that on the IL5‐dependent B13 cell line, the IL5R+ splenic B cell population does not differ from the vast majority of the rest of the splenic B cell pool with respect to surface phenotypes (except for expressing IL 5R), VH gene family utilization and autoreactivity.
Stimulation of cloned human T lymphocytes via the CD3 or CD28 molecules induces enhancement in vascular endothelial permeability to macromolecules with participation of type‐1 and type‐2 intercellular adhesion pathways
Authors: Damle Nitin K. , Doyle Laura V.
Published: March 2007

Perivascular accumulation of CD29+CD45R0+ memory T lymphocytes at sites of chronic inflammation such as rheumatoid synovium is commonly associated with the localized increase in the endothelial permeability. We have recently demon strated that a direct interaction between activated CD29+CD45R0+ memory T lymphocytes and vascular endothelial cells (EC) results in the increased permeability of EC. In this report, we have investigated effects on antigen‐specific T cell receptor (TcR) α/β+ human T lymphocyte clones on the endothelial permeability to albumin. Our results show that CD29+CD45R0+ cloned human T lymphocytes augment endothelial permeability by a noncytolytic process requiring surface contact between T lymphocytes and EC. Both cytolytic and noncytolytic cloned T lymphocytes were capable of augmenting endothelial permeability and this process did not involve active lysis of EC. Stimulation of T lymphocytes via the CD3/TcR or CD28 molecules resulted in significant enhancement in the ability of T lymphocytes to influence endothelial permeability. Pretreatment of T lymphocytes with monoclonal antibodies directed at either CD11a/CD18 (LFA‐1) or CD2 molecules or that of EC with monoclonal antibodies directed at either CD54 (ICAM‐1) or CD58 (LFA‐3) molecules significantly inhibited T lymphocyte‐induced enhancement in endothelial permeability, thus indicating that activated T lymphocytes utilize both type‐1 (CD11a/CD18CD54) and type‐2 (CD2CD58) intercellular adhesion pathways to augment endothelial permeability and signals received via CD3 or CD28 molecules on T lymphocytes further enhance this process. Furthermore, proinflammatory cytokines interleukin 1 and tumor necrosis factor but not interleukin 6 induced resistance in EC to T lymphocyte‐mediated effects on their permeability. Collectively, these observations may provide insights into molecular mechanism(s) underlying pathophysiology of localized chronic inflammatory responses in general and more specifically selective accumulation of chronically activated memory T lymphocytes at sites of chronic inflammation.
Intravascular metabolism of normal and mutant mouse immunoglobulin molecules
Authors: Pollock Roberta R. , French Deborah L. , Metlay Joshua P. , Birshtein Barbara K. , Scharff Matthew D.
Published: March 2007

The metabolism of IgG immunoglobulins in the body is tightly regulated in order to maintain their intravascular concentration. Different subclasses may have different intravascular half‐lives, and in the mouse, passively administered IgG2b disappears from the circulation more rapidly than IgG2a. We have attempted to localize the sequences in the constant region which are responsible for this difference by examining the intravascular metabolism of mutant immunoglobulins that were generated in tissue culture and have undergone deletions of individual constant region domains or contain different combinations of γ2b and γ2a CH2 and CH3 domains. Our results suggest that the regulation of intravascular metabolism is complex but indicate that sequences in the CH3 domain are important in determining the different intravascular half‐lives of IgG2b and IgG2a antibodies in the mouse.
Infection of Epstein‐Barr virus‐transformed lymphoblastoid B cells by the human immunodeficiency virus: evidence for a persistent and productive infection leading to B cell phenotypic changes
Authors: De Rossi Anita , Roncella Silvio , Calabro Maria Luisa , D'Andrea Emma , Pasti Marcella , Panozzo Marina , Mammano Fabrizio , Ferrarini Manlio , Chieco‐Bianchi Luigi
Published: March 2007

Four Epstein‐Barr virus‐positive lymphoblastoid cell lines (LCL) were successfully infected in vitro with immunodeficiency virus type 1 (HIV‐1) as demonstrated by reverse transcriptase activity and p24 HIV antigen in culture supernatants, positive cell staining for gag‐encoded HIV proteins, presence of viral HIV genome by Southern blot analysis and ulstrastructural observations. In addition, both HIV‐1‐infected B cells and their supernatants efficiently transactivated the chloramphenicol acetyl transferase reporter gene which is under the control of the HIV‐1 long terminal repeat.

The LCL cells displayed long‐term HIV‐1 infection and production, but no cytopathic effects were observed. Cytofluorimetric analysis did not detect membrane CD4 presence in the LCL cells before and after HIV‐1 infection; moreover, a minute amount of CD4 mRNA was observed only in one of the LCL. A monoclonal antibody specific for the viral binding site of the CD4 molecule delayed, but did not block, HIV‐1 infection of the LCL cells.

Following HIV‐1 infection, changes in LCL phenotype were observed, consisting of a decrease in CD23‐ and CD39‐positive cells, and a concomitant increase of cells with surface CD10 and Bac‐1. Furthermore, HIV‐1‐infected LCL cells did not grow in tight clumps, as usually observed in uninfected LCL, but as disperse suspensions, and formed more agar colonies than control LCL. However, despite this apparent acquisition of a malignant‐like phenotype, c‐myc proto‐oncogene rearrangement was not detected. The appearance of cells with new characteristics did not seem due to clone selection by HIV‐1 infection, since all the LCL conserved their clonotypic pattern of IgH chain rearrangement.

The acquisition of malignant‐like features by HIV‐infected B cells might be clinically significant in terms of the pathogenesis of non‐Hodgkin's B cell lymphomas, which occur frequently in AIDS patients.
Bone marrow transplantation from mutant lpr/lpr mice. Functional abnormalities rather than alloantigenic differences appear to determine the development of a graft‐vs. ‐host‐like syndrome
Authors: Allen Ruth D. , Marshall Jan D. , Roths John B. , Sidman Charles L.
Published: March 2007

Transfer of bone marrow (BM) from autoimmunity‐prone mice homozygous for the lymphoproliferation (lpr) mutation to irradiated congenic +/+ recipients has previously been shown to result in a syndrome similar to chronic graft‐vs.‐host (GVH) disease. It has been suggested that this syndrome may be due to an antigenic difference caused by the lpr mutation itself or to antigenic differences at loci closely linked to the lpr locus (Theofilopoulos, A. N. et al., J. Exp. Med. 1985. 162: 1; Mosbach‐Ozmen, L. and Loor, F., Thymus 1987. 9: 197). However, the results presented here indicate that alloantigenic differences do not play a role in this syndrome. Instead, the chronic disease observed in lpr/lpr→+/+ BM chimeras appears to develop as a result of a functional defect associated with the lpr mutation which is expressed shortly after transfer of lpr/lpr BM to irradiated recipients. This defect causes an increase in the levels of serum IgG1 and IgG2, which peak at 4–5 weeks post‐transfer and then decline to normal levels by 9–10 weeks post‐transfer. Inflammation similar to that observed in classic GVH reactions accompanies excess IgG production in congenic +/+ recipients but not in lpr/lpr recipients of lpr/lpr BM. We demonstrate that the GVH‐like response occurring in lpr/lpr→+/+ chimeras is dependent on mature T cells, but that either lpr/lpr or +/+ T cells can support this reaction. These results suggest that transfer of lpr/lpr BM to normal mice causes immunoregulatory disturbances which lead to nonspecific activation of T cells. We speculate that lpr/lpr BM causes a GVH‐like reaction in +/+ recipients but a systemic lupus erythematosus‐like syndrome in lpr/lpr recipients because of intrinsic differences in the +/+ and lpr/lpr host environments. Considering these findings, the lpr/lpr→+/+ GVH model may be useful for analysis of factors capable of inducing undesirable reactions in clinical BM transplantation between nominally histocompatible donors and recipients, in addition to being informative about the nature of the lpr mutation itself.
Tolerance to experimental contact sensitivity induced by T cell vaccination
Authors: Mekori Yoseph A. , Karin Nathan , Gottesman Giora , Cohen Irun R.
Published: March 2007

It was shown previously that experimental autoimmune diseases could be prevented or treated specifically by administering suitably attenuated autoimmune T lymphocytes to animals, a process termed T cell vaccination (Cohen, I. R., Sci. American 1988. 256: 52). We now report that T cell vaccination is an effective way of inducing tolerance to contact sensitivity to simple chemical haptens. Vaccines were prepared from populations of lymph node cells from specifically sensitized mice by activating the T cells with the T cell mitogen concanavalin A and then treating the T cell blasts with glutaraldehyde. The vaccinated mice showed decreased delayed sensitivity responses to the specific sensitizing antigen and developed significant delayed sensitivity responses to the T cells of the same specificity as those used for vaccination. Thus, T cell vaccination against contact sensitivity reactions appears to function similarly to T cell vaccination against autoimmune disease.
Analysis of the T cell repertoire for myelin basic protein in thymus‐grafted and other types of chimera: evidence that major histocompatibility complex molecules on accessory cells rather than T cell specificity mainly regulate susceptibility to autoimmune encephalomyelitis
Authors: Matsumoto Yoh , Kawai Kazuhiro , Fujiwara Michio
Published: March 2007

Experimental autoimmune encephalomyelitis (EAE) is a T cell‐mediated autoimmune disease inducible in rodents by immunization of brain‐specific antigens such as myelin basic protein (MBP). It is also well known that various strains of rats differ in their susceptibility to EAE upon active immunization. To elucidate the immune mechanisms of susceptibility and resistance to EAE, we first examined the T cell repertoire for MBP using thymectomized chimeras that possessed thymuses from EAE‐susceptible (LEW) or EAE‐resistant (BM) strains. It was revealed that T cell specificity of these chimeras was skewed toward that of the grafted thymus. Very interestingly, the chimeras bearing thymuses from the resistant strain developed severe EAE, keeping a hole in the encephalitogenic 68‐88 sequence of MBP. These findings suggest that the strain‐specific T cell repertoire itself is not involved in the regulation of EAE susceptibility. Furthermore, the analysis of the chimeras reconstituted with F1 T cells and marrow cells from various strains indicates that the major histocompatibility complex (MHC) molecules expressed on accessory cells primarily determine susceptibility or resistance to EAE. We finally showed, using various inbred and congenic rats carrying RT1l or RT1n, that susceptibility to EAE of rats carrying RT1l is heavily influenced by the background genes, whereas resistance to EAE of rats carrying RT1n is primarily regulated by the MHC molecules expressed on accessory cells without influence of the background genes.
Structures on the I‐A molecule predisposing for susceptibility to type II collagen‐induced autoimmune arthritis
Authors: Gustafsson Kenth , Karlsson Mikael , Andersson Leif , Holmdahl Rikard
Published: March 2007

The susceptibility to type II collagen (CII)‐induced arthritis (CIA) in mice is profoundly influenced by major histocompatibility complex (MHC) class II genes in the H‐2 region. Analyses of MHC‐congenic strains on the B10 background show that only strains developing an anti‐CII antibody response after immunization with autologous CII develop arthritis after induction with CII from various species. The susceptible haplotypes have been found to be H‐2q, H‐2r, H‐2w3 and H‐2w17. In addition, these haplotypes respond to different patterns of CII derived from various species suggesting that T cell receptors and CII peptides interact. In contrast, certain haplotypes closely related to H‐2q, such as the H‐2p and H‐2w5 haplotypes, are resistant to induction of CIA and are nonresponders to CII. We have earlier shown that a critical structure on the I‐Aβ molecule determines the susceptibility differences between the p and q haplotypes. We have now determined the structure of exon 2 of the Aβ as well as some of the Aα genes of the remaining haplotypes in the p, q and r families. The sequences show similarities between the CIA‐susceptible haplotypes in the Aβ C‐terminal part and the Aα N‐terminal part of the first domains forming a large part of the antigenic peptide‐binding site. Among the wild mouse‐derived haplotypes, the w5 haplotype showed an Aβ sequence identical to that of the p haplotype consistent with its nonresponder nature to CII immunization. These findings suggest that (a) structures shared between different class II molecules are of importance for the susceptibility to disease in mouse strains and (b) most likely recognition of different CII peptides is important for development of disease.
Critical role of an amino acid residue in a T cell determinant is due to its interaction with a neighboring non‐critical residue
Authors: Boyer Michel , Novak Zuzana , Fotedar Arun , Fraga Ester , Singh Bhagirath
Published: March 2007

Several lines of evidence support the concept of two functionally distinct sites on antigen: the epitope, involved in interaction with the T cell receptor and the agretope, interacting with Ia. We investigated the Ia and T cell receptor interaction sites on the synthetic polypeptide antigen poly‐18 [poly‐EYK(EYA)5] using T cell hybridoma clones specific for this antigen in the context of I‐Ad. Peptides with amino acid sequences related to poly‐18 were synthesized. These were used to identify the critical residues in the minimum peptide sequence required for activation. Clone A.1.1 responds to the minimal peptide EYK(EYA)4 but not to (EYA)5. This identifies Lys3 as a critical amino acid for this hybridoma. Surprisingly, the substituted peptide EYAEAA(EYA)3 could activate A.1.1, indicating that an Ala at position 5 instead of a Tyr obviates the critical requirement for Lys3. This demonstrates that the function of critical residues may extend beyond contacting the T cell receptor or Ia, to include a third role: that of interacting with other amino acids of the T cell epitope, thus influencing the antigen's recognition by T cells.
γ/δ T cells and α/β T cells differ in their developmental patterns of receptor expression and modulation requirements
Authors: George James F. , Cooper Max D.
Published: March 2007

Measurement of the cell surface levels of γ/δ (TcR1) and α/β (TcR2) T cell receptors in the chicken revealed that thymocyte subpopulations that express these receptor isotypes differ remarkably in their rates of receptor acquisition. Whereas TcR 1 expression was relatively high (> 104 sites per cell) beginning on day 12 of embryonic life, the initial levels of TcR2 expression on embryonic thymocytes were relatively low (approximately 103 sites per cell) when first measurable on day 15, and increased gradually as a function of T cell maturation. In peripheral tissues, the TcR 1 cells also expressed higher receptor levels than did the TcR 2 cells, but the difference was only 2–3‐fold. The TcR 2 receptors on immature T cells could be easily modulated by receptor cross‐linkage, very much like immunoglobulin receptors on immature B cells. While the TcR 2 receptor modulation occurred within minutes, TcR 1 receptor modulation required several hours for completion, even in the embryonic thymus. The data indicate very different developmental programs for TcR 1 and TcR 2 expression, and suggest fundamental differences in clonal selection modes for the two T cell subpopulations.
Presentation of endogenous immunoglobulin determinant to immunoglobulin‐recognizing T cell clones by the thymic cells
Authors: Rudensky Alexander Y. , Mazel Svetlana M. , Yurin Vitalij L.
Published: March 2007

Using immunoglobulin (Ig)‐recognizing T helper clones the expression of Ig peptide/major histocompatibility complex class II complexes derived by the processing of endogeneous Ig molecules in the thymus was demonstrated. It was found that thymic B cells but not “classic” thymic antigen‐presenting cells and macrophages represent the major antigen‐presenting cell type of determinants of endogenously synthesized surface Ig (Igx‐1b) and anti‐surface Ig antibodies (IdC3B9). The Igx‐1b‐presenting activity in the thymus appears relatively late, only after 3 weeks of postnatal life, while in the spleen an efficient presentation of endogenous Igx‐1b epitope is observed very early after birth. This difference between thymic and peripheral presentation of endogeneous Ig determinant could be important for understanding the mechanisms of T cell tolerance to self Ig and the role of self Ig in negative and positive selection of T cell repertoire.
Characterization of an IgA receptor from group B streptococci: specificity for serum IgA
Authors: Lindahl Gunnar , Åkerström Bo , Vaerman Jean‐Pierre , Stenberg Lars
Published: March 2007

Some strains of group B streptococci express a cell surface protein which binds IgA. This report describes some properties of such an IgA receptor and compares it with a previously described IgA receptor from group A streptococci. The group B receptor was released in an almost pure form from bacteria incubated at elevated pH, and could be isolated by IgA‐Sepharose affinity chromatography. The sequence of the N‐terminal 19 amino acid residues was unique. The receptor preferentially binds IgA of human origin, as shown in immunoblotting experiments with purified IgA from nine different species. The affinity constant of the purified receptor for serum IgA was determined to be 3.5 × 108 M−1, but for secretory IgA it was too low to allow determination. This result indicates that secretory component and/or J chain interferes with the binding of IgA to this type of bacterial receptor, which may be one of the physiological functions of these polypeptides. A reduction in affinity was also observed for another complexed form of IgA, α1‐microglobulin‐IgA. The group B receptor is antigenically unrelated to the IgA receptor from group A streptococci (protein Arp), but competitive inhibition experiments indicate that they bind to the same region in IgA. The implications of these findings, and the biological role of bacterial IgA receptors, are discussed.
Expression of the Epstein‐Barr virus (EBV)‐encoded membrane antigen (LMP) increases the stimulatory capacity of EBV‐negative B lymphoma lines in allogeneic mixed lymphocyte cultures
Authors: Cuomo Laura , Trivedi Pankaj , Wang Fred , Winberg Gösta , Klein George , Masucci Maria G.
Published: March 2007

Epstein‐Barr virus (EBV)‐negative Burkitt lymphoma (BL) lines are poor stimulators in allogeneic mixed lymphocyte cultures compared to EBV‐transformed lymphoblastoid cell lines derived from the same individuals. We have previously shown that the stimulatory capacity of the tumor cells is increased after EBV conversion (Avila‐Carino et al., Int. J. Cancer 1987. 40: 691). As a first step towards the identification of the viral gene product responsible for this change we have studied the influence of the EBV latent membrane protein (LMP) on the stimulatory capacity of the EBV‐negative BL lines BL41 and DG75 and the B lymphoma line BJAB.

Four LMP‐transfected sublines of BL41, four DG75 LMP transfectants and one LMP‐transfected subline of BJAB showed a significantly stronger stimulatory capacity than the original line. The effect was directly proportional to the amount of LMP detected in each transfectant but was not due to reactivation of LMP‐specific memory cells since lymphocytes from EBV‐seropositive and ‐seronegative individuals responded equally. In order to define the relation between LMP expression and induction of stimulatory capacity, DG75 was transfected with constructs containing the LMP gene under the control of an heat‐shock promoter. The peak of LMP expression in heat shock‐treated cells preceded the appearance of stimulatory capacity by 6–12 h suggesting that critical amounts of the protein may be required to induce the phenotypic change recognized by the T cells.

LMP influenced in a dose‐dependent manner the expression of the adhesion molecules LFA‐1, LFA‐3 and ICAM‐1 and B cell activation markers CD23 and CD39 in transfected sublines of BL41, but did not affect the expression of these markers in the DG75 and BJAB cell line. All LMP‐expressing transfectants showed an increased capacity to form conjugates with unprimed allogeneic lymphocytes.
Cross‐talk between B cell surface immunoglobulin and interleukin 4 receptors: the role of protein kinase C and Ca2+‐mediated signals
Authors: Klaus Gerry G. B. , Harnett Margaret M.
Published: March 2007

A well‐known property of IL 4 is its capacity to synergize with low concentrations of anti‐immunoglobulin (Ig) antibodies to induce B cells to synthesize DNA. Cross‐linking of surface Ig receptors stimulates phosphoinositide hydrolysis, with consequent production of two signals: the elevation of intracellular Ca2+ levels and activation of protein kinase C (PKC). Little is known about the second messengers utilized by interleukin (IL)4 receptors. In this study we have investigated the relative contributions of the two signals emanating from the ligation of surface Ig receptors to the synergistic activation of B cells by IL 4. We show that IL 4 plus carefully titrated concentrations of PKC‐activating phorbol esters [such as phorbol 12,13‐dibutyrate (PBu2)] induce cell cycle entry of virtually all murine B cells and substantial levels of DNA synthesis. Ca2+ ionophores, in contrast do not act as co‐mitogens with IL 4. However, a critical concentration of ionomycin further enhanced DNA synthesis induced by PBu2 plus IL 4. Taken together, these results suggest that PKC activation alone is sufficient to synergize with IL 4 in inducing B cells to enter cell cycle. However, the co‐mitogenic effects of anti‐Ig and IL 4 are evidently also dependent on Ca2+ signals. This interpretation is supported by the findings that cyclosporin, which abrogates the activation of lymphocytes by Ca2+‐dependent stimuli, inhibits B cell proliferation induced by anti‐Ig plus IL 4, but not the response to PBu2 plus IL 4.
Lymphocytes in thymoma: association with myasthenia gravis is correlated with increased number of single‐positive cells
Authors: Fujii Yoshitaka , Hayakawa Masanobu , Inada Keiji , Nakahara Kazuya
Published: March 2007

In the normal thymus the number of lymphocytes and the proportion of CD4+CD8+ double‐positive cells decrease as a function of age. Six thymomas in elderly patients without myasthenia gravis had a large number of double‐positive T cells, as seen in the normal thymic cortex. This suggests that the epithelial cells of thymoma have the function of cortical epithelium and can induce precursor T cells to differentiate to the double‐positive stage but not further. In seven thymomas with associated myasthenia gravis, however, there was a conspicuous population of mature single‐positive T lymphocytes. These mature T cells may include autoreactive T cells.
A stimulatory monoclonal antibody detecting T cell receptor diversity among idiotype‐specific, major histocompatibility complex‐restricted T cell clones
Authors: Bogen Bjarne , Lauritzsen Grete F. , Weiss Siegfried
Published: March 2007

A panel of independent BALB/c T cell clones responding to a peptide of the λ2315 immunoglobulin light chain (residues 91–101), in the context of I‐Ed, has previously been described. A monoclonal antibody (mAb; GB113) to the T cell receptor (TcR) of one of the clones, 4B2A1 (Vα1, Jα19; Vβ8.2, Dβ1.1, Jβ1.2) precipitates the α/β heterodimer from 4B2A1. However, GB113 does not bind DO11‐10.2 cells bearing a similar α/β heterodimer (Vα1.1, JαTT11; Vβ8.2, Dβ1.1, Jβ1.1). GB113 does not cross‐react with the TcR of the six other clones in the panel. Furthermore, the mAb does not bind polyclonal λ2315‐specific T cell lines except 4.4% of cells of line 4 from which 4B2A1 was cloned. The mAb only binds a negligible number (0.5%) of BALB/c thymocytes and peripheral T cells. Therefore, the epitope detected by GB113 is very rarely expressed on 91‐101. λ2315‐specific TcR or on TcR of normal T cells. Soluble GB113 induces T cell activation [measured as proliferation and interleukin (IL) 2, IL 3 and interferon‐γ production]. GB113‐induced T cell activation is enhanced by soluble anti‐CD4 and anti‐Thy‐1 mAb.
Poly(Glu60Ala30Tyr10) (GAT)‐induced IgG monoclonal antibodies cross‐react with various self and non‐self antigens through the complementarity determining regions. Comparison with IgM monoclonal polyreactive natural antibodies
Authors: González‐Quintial Rosana , Baccalá Roberto , Alzari Pedro Maria , Nahmias Clara , Mazza Gilbert , Fougereau Michel , Avrameas Stratis
Published: March 2007

Previous studies have shown that the antibodies of the preimmune repertoire are able to bind to various auto‐ and xenoantigens including chemical haptens. Sequence analysis of two such murine monoclonal IgM natural autoantibodies showed that they are encoded by unmutated germ‐line variable regions of the light and heavy chain (Vx and VH) genes which were also found in various murine immune responses, like phenyl‐oxazolone, dinitrophenyl, arsonate, phosphoryl‐choline and influenza virus hemagglutinin. These data raised the question as to whether induced antibodies possessing germ‐line sequence are also able to react with autoantigens. To study this problem, anti‐poly(Glu60Ala30Tyr10) (GAT) and anti‐alprenolol (Alp) monoclonal antibodies, carrying similar VH and Vx genes and the same IgG1 isotype, were examined for their capacity to react with several self and non‐self antigens. The results showed that: (a) the anti‐GAT antibodies tested reacted with different autoantigens, such as murine tubulin, actin and myosin as well as trinitrophenyl (TNP) and bovine serum albumin. Similarly, one of the anti‐Alp showed weak reactivities for myosin, DNA, actin and TNP; (b) in contrast two other anti‐Alp antibodies did not react with any of the tested antigens. Since the major differences between the oligoreactive anti‐GAT and the monoreactive anti‐Alp antibodies are in the complementarity determining regions (CDR) our results suggest that the observed cross‐reactions are mediated by hypervariable loops. Sequence comparison of these antibodies indicate a possible correlation between cross‐reactivity and the presence of aromatic and charged amino acids in the CDR.
Low IgG2 and polysaccharide response in a T cell receptor expression defect
Authors: Regueiro José R. , Perez‐Aciego Paloma , Aparicio Pedro , Martinez‐a Carlos , Morales Pablo , Arnaiz‐Villena Antonio
Published: March 2007

B lymphocytes require appropriate T lymphocyte cooperation to synthesize immunoglobulins (Ig). Such interaction presumably takes place after engagement of the T cell receptor (TcR) by antigen. The present work addresses B lymphocyte function (and phenotype) in a novel type of immunodeficiency which is characterized by a TcR expression defect. In contrast to expectations, the two affected siblings that were studied displayed normal in vivo antibody responses to both endogenous and exogenous protein antigens. However, they showed impaired responses to certain polysaccharide antigens together with a selective IgG2 deficiency. These results suggest that some polysaccharide responses may be more T cell dependent than previously suspected, and support the notion that T cell dysfunctions (of this or other kind), rather than Ig gene deletions, may be the molecular basis of certain IgG2 deficiencies. To rule out a concomitant gross B cell dysfunction in these individuals, B lymphocyte phenotype and function were assayed in vitro, and found to be normal. A T cell line derived from one of the siblings displayed an abnormal TcR on the cell surface, but it showed several normal TcR‐mediated functions. This suggests that the low number of peripheral T lymphocytes that have been found to express low TcR levels in these immunodeficiencies may be operational, and supplying sufficient “help” for the observed normal antibody responses to all tested protein, but not polysaccharide, antigens.
Characterization of B cell growth in systemic lupus erythematosus. Effects of recombinant 12‐kDa B cell growth factor, interleukin 4 and transforming growth factor‐β
Authors: Flescher Eliezer , Fossum Donna , Ballester Ana , Maizel Abby , Sharma Surendra , Talal Norman
Published: March 2007

B cells from systemic lupus erythematosus (SLE) patients have been shown to be hyperactive as measured by proliferation and immunoglobulin production. We find that B cells from 6 of 13 SLE patients, in the absence of prior activation, respond two to three times better to recombinant 12‐kDa B cell growth factor (BCGF) than do normal or rheumatoid arthritis B cells (p < 0.005). B cells from normally responsive SLE patients require an anti−μ antibody activation step to generate similar proliferative signal in response to r12‐kDa‐BCGF. There are no clinical or serological parameters that distinguish these hyperresponsive SLE patients from the normally responsive SLE patients. The combination of r12‐kDa‐BCGF and interleukin 4 (IL 4) gives an enhanced response with both normal and SLE B cells. Transforming growth factor type β (TGF‐β) suppresses the response to r12‐kDa‐BCGF in a dose‐dependent fashion using B cells from both healthy donors and SLE patients. We conclude that peripheral blood B cells are in an activated state (as detected by response to 12‐kDa‐BCGF) in approximately 50% of SLE patients. These B cells respond normally to regulation by IL 4 and TGF‐β. A therapeutic approach aimed at reducing the B cell hyperactivity in SLE would involve suppressing the effects of 12‐kDa‐BCGF and IL 4 while at the same time enhancing the effects of TGF‐β.
Dual effect of ciliary body cells on T lymphocyte proliferation
Authors: Helbig Horst , Gurley Rebecca C. , Palestine Alan G. , Nussenblatt Robert B. , Caspi Rachel R.
Published: March 2007

The interaction between organ‐resident cells from the anterior uvea of the eye and T helper (Th) cells was investigated. Cells from Lewis rat ciliary body processes (CB cells), grown in tissue culture using an explant technique, could be induced to express major histocompatibility complex class II (la) antigens by incubation with rat interferon‐gamma. Ia+ CB cells only poorly functioned as antigen‐presenting cells (APC) for a syngeneic, uveitogenic Th cell line specific for the retinal soluble antigen (SAg). Moreover, if added to an Ag‐driven lymphocyte proliferation assay in the presence of conventional APC, the rat CB cells had an inhibiting effect on Th proliferation. This inhibitory activity was not species specific, since similar effects were observed with bovine and human ciliary epithelial cells. The suppressive activity of CB cells was composed of a soluble factor, as well as a membrane‐associated inhibitor. The soluble activity did not appear to be related to transforming growth factor‐beta (TGF‐β), since no reversal of inhibition by a neutralizing antibody to TGF‐β was found. Part of the soluble inhibitory activity could be reversed by indomethacin treatment. The membrane‐associated component was trypsin sensitive, suggesting a protein molecule. After abrogation of the inhibitory capacity by trypsin treatment and fixation by glutaraldehyde, CB cells effectively presented SAg to Th cells. These data suggest that CB cells are capable of mediating both Ag presentation and inhibition of Th cell proliferation.
Cytokine‐stimulation of prostaglandin synthesis from endogenous and exogenous arachidonic acids in polymorphonuclear leukocytes involving activation and new synthesis of cyclooxygenase
Authors: Herrmann Friedhelm , Lindemann Albrecht , Gauss Jutta , Mertelsmann Roland
Published: March 2007

Peripheral blood‐derived human polymorphonuclear leukocytes (PMNL) can be induced to synthesize prostaglandin E2 (PGE2) from endogenous and exogenous arachidonic acid (AA) when exposed to agents such as human recombinant (hr) granulocyte‐macrophage (GM) colony‐stimulating factor (CSF), hr tumor necrosis factor‐α, hr granulocyte (G)‐CSF, lipopolysaccharide and the chemoattractant N‐formyl‐methionyl‐leucyl‐phenylalanine. Treatment of PMNL with hr macrophage (M)‐CSF and interleukin 3, however, did not result in detectable PGE2 synthesis. Cytokines stimulated PGE2 production during two distinct time intervals, an early peak of PGE2 that was detectable at 20 min and a late one detectable after 4 h. Inhibition of protein synthesis by cycloheximide (CHX) had virtually no effect on the early increase of PGE2 but prevented the late increase. Late addition of CHX to cultures after stimulation with hr GM‐CSF at 4 h resulted in decline of PGE2 synthesis from exogenous arachidonic acid. Treatment of PMNL with GM‐CSF had direct effects on cyclooxygenase (COx). PMNL depleted from COx by acetyl salicylic acid (ASA) recovered to synthesize PGE2 following exposure to GM‐CSF. Recovery from COx inhibition by ASA could be prevented by CHX.