Restriction fragment length polymorphisms of the mouse T-cell receptor gene families

T cell receptor-gamma allele-specific selection of V gamma 1/V delta 4 cells in the intestinal epithelium

Previous genetic analyses have shown that the relative representation of subsets of gammadelta intestinal intraepithelial lymphocytes (i-IELs) is influenced by genes linked to the TCRgamma, TCRdelta, and MHC loci. Here, we have analyzed V-gene use in gammadelta i-IELs from C57BL/6 (B6) and C57BL/10 (B10) mice and from their F(1) and F(2) progenies with a larger panel of Vgamma- and Vdelta-specific mAbs and have shown that the influence of TCRgamma-linked genes operates at two levels: one influencing the representation of Vgamma1 (or Vgamma7) i-IELs and other acting specifically on the Vgamma1/Vdelta4 i-IEL subset, which represents 3% and 15% of the gammadelta i-IELs in B6 and B10 mice, respectively. Analysis of mice transgenic for a rearranged Vgamma1Jgamma4Cgamma4 chain of B6 origin demonstrated that the TCRgamma-linked genes influencing the representation of the Vgamma1/Vdelta4 i-IEL subset are the structural genes of TCRgamma chains. This influence is allele specific and cell autonomous, as evidenced by the different behavior of Vgamma1/Vdelta4 cells bearing either parental allele in F(1) mice. The representation of Vgamma1/Vdelta4 cells among gammadelta thymocytes is similar in B6 and B10 mice, demonstrating that the Vdelta4 chain can pair well with both alleles of the Vgamma1Jgamma4Cgamma4 chain and strongly suggesting that a cellular selection mechanism is responsible for the observed differences. The Vgamma1-Jgamma4 junctional amino acid sequences of B6 Vgamma1/Vdelta4 i-IELs are diverse but display less variation in length than those found in similar cells from B10 mice, indicating that B6 Vgamma1/Vdelta4 cells are the target of this cellular selection event.

Strain-specific TCR repertoire selection of IL-4-producing Thy-1 dull gamma delta thymocytes

Thy-1 dull gamma delta thymocytes constitute an unusual subset of mature TCR gamma delta cells which share with NK T cells the expression of cell surface markers usually associated with activated or memory cells and the simultaneous production of high levels of IL-4 and IFN-gamma upon activation. In DBA / 2 mice, Thy-1 dull gamma delta thymocytes express a restricted repertoire of TCR that are composed of the V1 gene product mainly associated with V6.4 chains exhibiting very limited junctional sequence diversity. In this study we have characterized this gamma delta T cell population in different strains of mice and show that Thy-1 dull gamma delta thymocytes are present in every strain tested, albeit at different frequencies. Moreover IL-4 production by gamma delta thymocytes is mainly confined to the Thy-1 dull population in every strain tested. Finally, the repertoire of TCR expressed by Thy-1 dull gamma delta thymocytes varies in different strain of mice, although a biased expression of Vgamma1 and Vdelta6 chains was observed in all strains studied. However, the extent of junctional diversity of the V1 and V6 chains expressed by Thy-1 dull gamma delta thymocytes varied from oligoclonal in DBA/2 mice to polyclonal in FVB/N mice. Thy-1 dull gamma delta thymocytes from mouse strains such as C3H/HeJ and BALB/c contain cells with diverse Vdelta6(D)Jdelta junctions together with cells with relatively homogeneous Vdelta6(D)Jdelta junctions, similar to those found in DBA/2. Thus, the Thy-1 dull gamma delta population appears to contain two subsets of cells which differ in the diversity of their TCR.

Genetic mapping of two murine loci that influence the development of IL-4-producing Thy-1dull gamma delta thymocytes

IL-4-producing gamma delta cells belong to a novel subset of gamma delta lymphocytes that expresses a very restricted repertoire of TCRs. To gain a deeper insight into the development and in vivo functions of these cells, we have analyzed the genetic control of their representation in the thymus. Using an intercross between C57BL/6 and DBA/2 mice we found two loci on chromosomes 13 and 17-named LadT1 and LadT2, respectively-with marked influence in their development. The LadT2 locus does not appear to be the MHC locus. The region identified on mouse chromosome 13 contains the structural genes for TCR gamma as well as the IL-9 gene, which has been suggested as a candidate gene influencing the complex pathogenesis of asthma.

IL-4-Producing γδ T Cells That Express a Very Restricted TCR Repertoire Are Preferentially Localized in Liver and Spleen

IL-4-producing γδ thymocytes in normal mice belong to a distinct subset of γδ T cells characterized by low expression of Thy-1. This γδ thymocyte subset shares a number of phenotypic and functional properties with the NK T cell population. Thy-1dull γδ thymocytes in DBA/2 mice express a restricted repertoire of TCRs that are composed of the Vγ1 gene product mainly associated with the Vδ6.4 chain and exhibit limited junctional sequence diversity. Using mice transgenic for a rearranged Vγ1Jγ4Cγ4 chain and a novel mAb (9D3) specific for the Vδ6.3 and Vδ6.4 murine TCRδ chains, we have analyzed the peripheral localization and functional properties of γδ T cells displaying a similarly restricted TCR repertoire. In transgenic mice, IL-4 production by peripheral γδ T cells was confined to the γδ+9D3+ subset, which contains cells with a TCR repertoire similar to that found in Thy-1dull γδ thymocytes. In normal DBA/2 mice such cells represent close to half of the γδ T cells present in the liver and around 20% of the splenic γδ T cells.

Reciprocal Expression in CD4 or CD8 Subsets of Different Members of the Vα11 Gene Family Correlates with Sequence Polymorphism

Previous staining studies with TCR Vα11-specific mAbs showed that Vα11.1/11.2 (AV11S1 and S2) expression was selectively favored in the CD4+ peripheral T cell population. As this phenomenon was essentially independent of the MHC haplotype, it was suggested that AV11S1 and S2 TCRs exert a preference for recognition of class II MHC molecules. The Vα segment of the TCR α-chain is suggested to have a primary role in shaping the T cell repertoire due to selection for class I or II molecules acting through the complementarity determining regions (CDR) 1α and CDR2α residues. We have analyzed the repertoire of Vα11 family members expressed in C57BL/6 mice and have identified a new member of this family; AV11S8. We show that, whereas AV11S1 and S2 are more frequent in CD4+ cells, AV11S3 and S8 are more frequent in CD8+ cells. The sequences in the CDR1α and CDR2α correlate with differential expression in CD4+ or CD8+ cells, a phenomenon that is also observed in BALB/c mice. With no apparent restriction in TCR Jα usage or CDR3α length in C57BL/6, these findings support the idea of Vα-dependent T cell repertoire selection through preferential recognition of MHC class I or class II molecules.

Use of TCR ADV gene segments by the delta chain is independent of their position and of CD3 expression

The CD3 signaling complex is required for cell surface expression and selection of both alphabeta and gammadelta TCR. In this study we analyzed TCRD transcripts in both wild-type and CD3-epsilon-deficient mice. We show that the repertoire of ADV segments used by the delta chain is unchanged in the latter. Not all ADV genes participate in making up the TCRD repertoire. However, their use does not depend on their distance from the other TCRD-forming segments. For example ADV12, situated at more than 870 kb from the DD region, is expressed as part of TCRD transcripts, whereas ADV8, members of which are proximal to the DD region, is not. These data suggest that the accessibility of ADV8 gene segments is differentially regulated during T cell development in the thymus. Taken together, our results suggest that TCRA and TCRD rearrangements are independently controlled, and that the absence of TCRA expression in CD3-epsilon-deficient mice is not due to a lack of accessibility of the ADV gene segments but rather to inaccessibility of the AJ gene region.

Differential chronology of TCRADV2 gene use by alpha and delta chains of the mouse TCR

The genes coding for TCR alpha and delta chains share the same genetic locus (TCRA/D). The rules governing the utilization of a V gene with the alpha and delta chains have not been established. More specifically, it is not known whether the position of a gene within the locus influences its utilization in alpha and delta TCR. To elucidate these points, we mapped ADV2 genes in the TCRA/D locus of BALB/c mice and analyzed their utilization in TCR alpha and delta transcripts from thymi isolated from mice of different ages. Our results show that all ADV2 genes can be used by the two chains, but with strikingly different patterns. Moreover, ADV2 utilization by the alpha chain proceeds in successive concentric waves during development, suggesting a progressive regulation of gene accessibility and utilization. These results support independent control of TCRA and TCRD gene assembly.

Polymorphism Within a TCRAV Family Influences the Repertoire Through Class I/II Restriction

Antibody-staining experiments have shown that closely related members of the TCRAV3 family are reciprocally selected into the CD4 or CD8 peripheral T cell subsets. This has been attributed to the individual AV3 members interacting preferentially with either MHC class I or MHC class II molecules. Single amino acid residues present in the complementarity-determining regions (CDR) CDR1α and CDR2α are important in determining MHC class specificity. We have now extended these observations to survey the expressed repertoire of the AV3 family in C57BL/6 mice. Three of the four expressed AV3 members are preferentially selected into the CD4+ subset of T cells. These share the same amino acid residue in both CDR1α and CDR2α that differ from the only CD8-skewed member. Preferential expression of an individual AV3 is not caused by other endogenous α- or β-chains, by any conserved CDR3 sequence, or by the usage of TCRAJ regions. This study shows that residues in the CDR1 and CDR2 regions are primary determinants for MHC class discrimination and suggests that polymorphism found within a TCRAV family has an important effect on the overall shaping of the T cell repertoire.

Genetic linkage of IgG autoantibody production in relation to lupus nephritis in New Zealand hybrid mice

F1 hybrids of New Zealand black (NZB) and New Zealand white (NZW) mice are a model of human systemic lupus erythematosus. These mice develop a severe immune com-plex-mediated nephritis, in which antinuclear autoantibodies are believed to play the major role. We used a genetic analysis of (NZB x NZW)F1 x NZW backcross mice to provide insight into whether different autoantibodies are subject to separate genetic influences and to determine which autoantibodies are most important in the development of lupus-like nephritis. The results showed one set of loci that coordinately regulated serum levels of IgG antibodies to double-stranded DNA, single-stranded DNA, total histones, and chromatin, which overlapped with loci that were linked to the production of autoantibodies to the viral glycoprotein, gp70. Loci linked with anti-gp70 compared with antinuclear antibodies demonstrated the strongest linkage with renal disease, suggesting that autoantibodies to gp70 are the major pathogenic antibodies in this model of lupus nephritis. Interestingly, a distal chromosome 4 locus, Nba1, was linked with nephritis but not with any of the autoantibodies measured, suggesting that it contributes to renal disease at a checkpoint distal to autoantibody production.

Mouse T-cell receptor variable gene segment families

All mouse T-cell receptor alpha/delta, beta, and gamma variable (Tcra/d-, b-, and g-V) gene segments were aligned to compare the sequences with one another, to group them into subfamilies, and to derive a name which complies with the standard nomenclature. It was necessary to change the names of some V gene segments because they conflicted with those of other segments. The traditional classification into subfamilies was re-evaluated using a much larger pool of sequences. In the mouse, most V gene segments can be grouped into subfamilies of closely related genes with significantly less similarity between different subfamilies.

T-cell receptor alpha haplotype influences V alpha epitope expression on both cortisone-resistant thymocytes and lymph node T cells

We have previously described a mouse strain congenic for the T-cell receptor alpha chain locus (Tcra). The strain, B10.D2.C-Tcraa/Bo, carries the Tcraa haplotype of BALB/c instead of the Tcrab haplotype normally found in B10.D2. By comparing B10.D2.C-Tcraa and B10.D2 mice, we now show that the Tcra haplotype influences the frequencies of V alpha 8 epitope expression on T cells detected by the novel B21.14 monoclonal antibody (MoAb). This finding agrees well with our previous observation that Tcra haplotype influences the frequencies of expression of two other V alpha 8 epitopes, detected by the KT50 and KT65 MoAbs. The specificities of the three V alpha 8-specific MoAbs were compared by scatter diagram analysis of staining frequencies obtained in individual mice. The B21.14 and KT50 MoAbs appear to have very similar specificities; these two MoAbs stain slightly more alpha beta T cells than the KT65 MoAb. Investigations with another novel MoAb, the V alpha 2-specific B20.1, revealed that the Tcra haplotype also influences the frequency of V alpha 2 epitope expression. The effect of the Tcra haplotype on V alpha 2 epitope expression was evident not only among lymph node T cells but also among mature, cortisone-resistant thymocytes. Thus, the influence of the Tcra haplotype is imprinted already in the thymus. The most likely explanations for Tcra haplotype dependency of V alpha epitope expression are differing numbers of V alpha-gene segment subfamily members and/or allelic polymorphism. The significance of Tcra haplotype-dependent V alpha epitope expression is discussed.

The IE allogeneic response of T cells from C57Bl/6 mice is associated with genes in the TCRa locus

It has been demonstrated that induction of immune responses, infectious diseases and autoimmune manifestations can be associated with at least four gene loci: the major histocompatibility complex (MHC) locus; the immunoglobulin (Ig) heavy chain (Hc) locus; and the T-cell receptor (TCR) TCR-alpha or TCR-beta chain loci. In the present study, we have analysed whether T-cell responses of IE-negative C57Bl/6 (B6) mice to IE alloantigen (IE alpha transgenic B6 mice = B6.E alpha 16) or to trinitrophenylated (TNP) syngeneic spleen cells were influenced by changes in the Ig-Hc locus or the TCRa locus. Whereas the fine specificity of T-cell responses to IE alloantigen was the same in B6 mice and in Ig-Hc congenic B6.26a or TCRa congenic B6.10TCa mice, the latter strain of mice demonstrated much higher IE-specific T-cell responses against B6.E alpha 16 spleen cells than B6 or B6.26a mice. This high responsiveness was a dominant feature and associated with the TCRa locus. In addition, the TCRV alpha or V beta repertoire of the congenic strains of mice was polyclonal and very similar. The TNP-specific T-cell responses of B6 and B6.10TCa mice showed the same restricted TCRV alpha and V beta repertoire. It is concluded that in both an oligoclonal T-cell response (anti-TNP) and a polyclonal T-cell response (anti-IE), exchange of Ig-Hc or TCRa loci does not significantly influence the TCRV alpha or V beta repertoire in IE-negative C57Bl/6 mice.

Co-selection of the rare T cell receptor-gamma B haplotype in mouse lines selected for low responsiveness to red blood cell antigens

T cell receptor (TcR)-gamma haplotype was investigated in seven pairs of murine Biozzi lines selected for low and high antibody (Ab) response to different antigens (Ag). High-responder lines (H) express gamma A or gamma C haplotypes irrespective of the selecting Ag. In contrast, the gamma B haplotype, which is rare in laboratory mouse strains, is found in all low-responder lines (L) to sheep erythrocyte Ag (SE). However, the TcR-gamma B locus might only have a low penetrance in the control of the SE response. Moreover, investigations using LIVA mice, which were selected for low SE response from homozygous gamma A founder parents, indicate that the gamma B haplotype is neither necessary nor sufficient to achieve a low-responder phenotype. The gamma B haplotype might, thus, be co-selected to confer to L mice an improved resistance to bacterial infections mediated by gamma delta T cells compensating the profound and nonspecific immune perturbation associated with the low Ab response.

New T-cell receptor gamma haplotypes in wild mice and evidence for limited Tcrg-V gene polymorphism

Tcrg gene polymorphism was investigated by Southern blot analysis on a panel of laboratory and wild mouse strains using a set of probes which identify all known Tcrg-V and -C genes. Only three haplotypes are found in laboratory mice: gA, gB, and gC which are represented by BALB/c, AKR, and DBA/2 prototypes respectively. gA and gC haplotypes are the most frequent among laboratory mice whereas gB is poorly represented. Seven new haplotypes are described among 23 wild mice corresponding to four Mus musculus subspecies (Mus mus domesticus, castaneus, musculus, and molossinus). However, only a few new alleles of individual genes are observed. Tcrg-V genes located at the 5' end of the Tcrg locus (V7 and V4) appear to be nonpolymorphic whereas two Tcrg-V3, -V5, -V6, -C4 and three Tcrg-V1, -V2, -C1, -C2, and -C3 specific restriction fragment length polymorphisms are detected. These results indicate a relatively high degree of conservation of Tcrg genes as compared to other members of the immunoglogulin (Ig) gene family and might be related to the specifity and function of gamma delta T cells. Several of the new haplotypes described here result from point mutations in noncoding Tcrg-V or -C gene-flanking regions. Recombinations may have also participated in the evolution of the Tcrg locus. Finally, these new Tcrg haplotypes are unequally distributed among the four M. m. subspecies and support the idea that the gA and gC haplotypes found in laboratory mice are inherited from M. m. domesticus whereas gB might originate from asian subspecies (castaneus, musculus or molossinus).

Structure-function relationship among T-cell receptors specific for lysozyme peptides bound to Ab or Abm-12 molecules

The alpha beta T-cell receptor (TCR) recognizes antigenic peptides bound to major histocompatibility complex (MHC) molecules. In contrast to the antibody combining site, for which the antigen contact or complementarity-determining residues (CDRs) have been precisely defined, the location and function of the corresponding CDR regions of the alpha and beta TCR chains are not known. To develop a model system for systematic analysis of the CDRs of the alpha beta TCR, we isolated a panel of murine T-cell clones that recognize a lysozyme peptide containing residues 74-88 bound to either Ab or Abm-12 MHC class II molecules. Although these two MHC molecules differ by only three amino acid residues within the A beta chain, each of the T-cell clones was specific for peptide bound to the self-MHC molecule and did not recognize the same peptide bound to the other MHC molecule. The structural basis for this exquisite ligand specificity of the TCRs was analyzed by isolation and characterization of alpha and beta chain genes from five closely related T-cell clones. Comparison of predicted amino acid sequences mapped the ligand specificity differences to residues present within the alpha chain variable region segment and the alpha and beta chain variable-joining region junction regions. Thus with current models of TCR-ligand interactions, the results suggest that residues 26-30 of the alpha chain variable region may constitute one of the CDR regions of the TCR.

Analysis of the T cell receptor (TcR) regions in the NOD, NON and CTS mouse strains define new TcR V alpha haplotypes and new deletions in the TcR V beta region

We have analyzed the T cell receptor (TcR) V alpha and TcR V beta regions in the spontaneous mouse model for insulin-dependent diabetes mellitus, the NOD mouse, and compared it to the regions in the two sister strains, the NON and CTS strains. Based on restriction fragment length polymorphism analysis the TcR V alpha region in the NOD mouse is essentially identical to that of the SJL/J strain. In contrast both the NON and CTS strains have a unique TcR V alpha haplotype. Whereas the NOD and NON strains apparently contains all the TcR V beta genes, the CTS mouse has three deletions in the V beta region. Our analysis does not give any indications for the diabetic phenotype of the NOD mouse.

Monoclonal antibodies raised against engineered soluble mouse T cell receptors and specific for V alpha 8-, V beta 2- or V beta 10-bearing T cells

We have characterized a panel of monoclonal antibodies (mAb) produced by immunizing rats with two distinct soluble mouse alpha/beta T cell receptor (TcR). Fifty mAb were found to react with the corresponding surface-bound TcR. Such observations suggest that the soluble TcR molecules used as immunogen are folded in a conformation similar to the native structure. Furthermore, the binding to T cells of four antibodies was found to correlate with the expression of the V alpha 8, V beta 2 or V beta 10 gene segments. Finally, staining of T lymphocytes from various mouse strains suggests that (a) the two anti-V alpha 8 antibodies recognize different epitopes, and each on only a fraction of V alpha 8+ cells; (b) the anti-V beta 10 mAb identifies a V beta 10 polymorphism among mouse strains, and (c) T cells expressing the V beta 2 or V beta 10 gene segments are not subject to major clonal deletion events induced by the major histocompatibility complex class II and Mls products which were tested.

Human T-cell receptor V alpha gene polymorphism

Polymorphism in the germline repertoire of T-cell receptor (TCR) variable alpha and beta (V alpha and V beta) genes could alter the relative abilities of individuals in a population to respond to particular antigens. Variation in the number of germline V alpha and V beta gene segments has been reported in wild mice and in different inbred mouse strains. A previous study of the human V beta gene germline repertoire failed to reveal a similar degree of polymorphism in the numbers of V beta gene segments. We have now carried out a survey of 10 different V alpha gene segment subfamilies containing approximately 23 V alpha gene segments in a panel of 120 unrelated individuals by hybridization and failed to find any evidence for V alpha repertoire polymorphism. To determine if significant germline polymorphism does occur in humans at the level of individual V gene segments, we determined the nucleotide sequences of eight copies of the V alpha 21 gene segment derived from seven unrelated individuals. Polymorphic differences between these sequences defined three different alleles. One of these alleles contains a frameshift mutation which would cause premature termination of the protein product. The presence of this null allele among the eight sequences determined suggests that functionally relevant germline polymorphism of human TCR V gene segments may occur by mechanisms other than gene duplication or deletion.

Profound alteration in an alpha beta T-cell antigen receptor repertoire due to polymorphism in the first complementarity-determining region of the beta chain

Amino acid residues that are critical in maintaining the framework structure of immunoglobulin heavy- and light-chain variable (V) regions are strongly conserved in the V alpha and V beta proteins of the alpha beta T-cell antigen receptor (TCR alpha beta). Consequently, it has been proposed that TCR alpha beta has a conformation similar to that of an immunoglobulin Fab fragment and that the regions of the TCR homologous to the three immunoglobulin complementarity-determining regions (CDRs 1, 2, and 3) bind to the peptide antigen-major histocompatibility complex (MHC) molecule ligand. A single amino acid substitution in the predicted CDR1 of the V beta 3 protein of certain mouse strains dramatically altered TCR alpha beta usage in an antigen-specific MHC-restricted immune response but did not abrogate V beta 3 specificity for the superantigens minor lymphocyte stimulatory locus (Mls)c and staphylococcal enterotoxin A (SEA). The results confirm the importance of the V beta CDR1 in antigen-MHC molecule recognition, supporting the Fab-like structural model of TCR alpha beta, and provide further evidence that conventional antigen-MHC recognition and superantigen recognition are mediated by distinct regions of the TCR beta chain. They also suggest that allelic polymorphism may be a significant source of diversity in the TCR repertoire.

The contribution of non-MHC genes to susceptibility to autoimmune diseases

Genetic studies of experimental models of autoimmune diseases, including systemic lupus-like syndromes and organ-specific autoimmunity, provide major information on genetic control of autoimmune diseases. In addition to genes known to be linked to the major histocompatibility complex (MHC), these studies point to multiple genes located outside the MHC that influence the onset and the progression of autoimmune diseases. Identification of these genes and of their interrelationships is now a major task that will be facilitated by recent progress in molecular biology and gene mapping. Among candidate genes, antigen-receptor genes (i.e., immunoglobulin- and T-cell receptor genes) most likely contribute an important part of the autoimmune susceptibility in several of these animal models. Available linkage data suggest a similar involvement of these antigen-receptor genes in several human autoimmune diseases. In addition to a better understanding of pathogenic mechanisms associated with autoimmunity, the knowledge of these disease-predisposing genes is expected to permit a better classification of often complex syndromes as well as the design of new treatments.

The role of C5 and T-cell receptor Vb genes in susceptibility to collagen-induced arthritis

Collagen-induced arthritis (CIA) is a rodent arthritis model in which immunization with heterologous type II collagen induces an inflammatory polyarthritis. Susceptibility to the disease is mediated by major histocompatibility complex (MHC) genes as well as genes at other loci. Previous studies of the SWR/J mouse strain, which is resistant to CIA despite bearing the susceptible H-2q haplotype, have suggested that this resistance is the result of a deletion of T-cell receptor (Tcr) Vb gene segments which is carried by this strain. Other studies have implicated a deficiency in complement component C5 as the cause for the resistance. In order to assess the relative importance of these two genes in susceptibility to CIA, and to provide an estimate of the number of independent genes involved in the disease, we analyzed 196 F2 progeny of a (DBA/1 x SWR/J) cross for arthritis susceptibility, and expression of both C5 and Tcr genes. Thirty of the F2 progeny developed arthritis. All of the arthritic mice had at least one copy of the wild-type C5 allele, while the Tcr-Vb haplotypes were distributed in Mendelian fashion. These results demonstrate that C5 sufficiency is an absolute requirement for CIA, but that Tcr-Vb genes located within the SWR deletion have little influence. Genetic analysis of the incidence rate suggests that there is polygenic control of susceptibility to CIA and that in addition to H-2, 5-6 other independent loci (including C5) may be involved.

The T cell receptor repertoire influences V beta element usage in response to myoglobin

T cell clones recognizing the sperm whale myoglobin (SpWMb) epitope 110-121 in association with H-2d major histocompatibility complex class II molecules display a very limited heterogeneity of T cell receptor (TCR) V beta usage in DBA/2 mice. All clones previously tested used the same V beta 8.2 gene segment and very restricted junctional regions. To investigate the significance of this observation in vivo, we immunized DBA/2 mice with the intact SpW Mb protein or peptide 110-121. Only the V beta 8+ T cells showed any significant response to the 110-121 epitope. The response to peptide 110-121 was then analyzed in mice which, either as a consequence of antibody depletion or through genetic deletion of TCR V beta genes, lacked V beta 8+ peripheral T cells. DBA/2 mice depleted of V beta 8+ T cells by antibody treatment responded poorly to the 110-121 peptide, and only at high antigen concentrations. In contrast, DBA/2V beta a mice (homozygous for a deletion of multiple V beta gene segments including the V beta 8 family) made a response at least as great as that made by DBA/2 mice, even though the DBA/2V beta a mice had a very restricted TCR V beta repertoire compared with DBA/2 mice. Mechanisms which might determine differences in the 110-121 specific response of DBA/2, DBA/2V beta a and F23.1-treated DBA/2 mice are discussed.

A rapid method for genotyping mice for T cell receptor V beta a and V beta b haplotypes by PCR analysis of whole blood

Strains of laboratory mice bearing a germline deletion of some T cell receptor V beta genes have proven useful in a variety of studies of T cell receptor function. Analysis of genetic crosses between deleted and wild type strains can provide information about the relevance of genes located within the deletion to specific T cell responses. Existing techniques for genotyping offspring of such crosses usually involve flow cytometric analysis which may not be available to all laboratories. Recent nucleotide sequence data indicate the presence of two restriction enzyme site polymorphisms in the closely linked V beta 1 gene which discriminate between deleted and wild-type strains. Amplification of a DNA segment containing the diagnostic sites by polymerase chain reaction followed by restriction enzyme digestion of the product offers a simple and rapid method for genotyping animals.

Autoimmune diseases: the failure of self tolerance

The ability to discriminate between self and nonself antigens is vital to the functioning of the immune system as a specific defense against invading microorganisms. Failure of the immune system to "tolerate" self tissues can result in pathological autoimmune states leading to debilitating illness and sometimes death. The induction of autoimmunity involves genetic and environmental factors that have focused the attention of researchers on the trimolecular complex formed by major histocompatibility complex molecules, antigen, and T cell receptors. Detailed molecular characterization of these components points to potential strategies for disease intervention.

Cellular and molecular characteristics of transformed T cells from an antigen-specific T-cell line

An antigen-specific T-cell line which transforms into T-lymphoma cells in vitro but apparently not in vivo is described. Membrane markers, tumorigenicity and T-cell receptor (TcR) V alpha and V beta-gene usage of the in vitro transformed T-cell line were analysed to investigate whether the transformation event was poly-, oligo-, or monoclonal. The results indicate that the T lymphoma has no chromosome abnormalities, contains no tumour-inducing virus, can induce clone-specific immunity, and is oligoclonal with respect to TcR V alpha and V beta expression. The nature of the transformation event and clinical application of vaccination against T lymphomas is discussed. In addition, the expressed TcR V alpha and V beta repertoire of Con A T blasts was apparently not affected by the Igh-l or the MHC haplotype, as investigated in Igh-l and MHC congeneic C57Bl mice.

Polymorphism of T-cell receptor genes among laboratory and wild mice: diverse origins of laboratory mice

Southern blots of genomic DNA from 23 strains of laboratory mice and 19 individual wild mice were examined for restriction fragment length polymorphisms in their loci encoding the T-cell receptors (Tcr): the constant regions of the alpha, beta, and gamma chains (C alpha, C beta, and C gamma) and a variable region family of the beta chain (V beta 8). Only a few polymorphisms were observed for each locus in the laboratory mice after using three restriction enzymes, Bam HI, Eco RI, and Hind III. All the laboratory mice examined fall into one of two types for the C alpha, C beta, and V beta 8 loci and one of three types for the C gamma. These types are found in some of the wild mice studied, indicating that they were already present in the founder mice of laboratory mouse strains. In contrast, the Tcr genes are highly polymorphic among wild mice. Analysis of the polymorphisms in these loci suggests that laboratory mice have inherited their genes not only from Mus musculus domesticus, but also from other subspecies, and much more than previously believed from Asian subspecies.

How some T cells escape tolerance induction

A feature common to many animal models of autoimmune disease, for example, experimental allergic encephalomyelitis, experimental autoimmune myasthenia gravis and collagen-induced arthritis, is the presence of self-reactive T cells in healthy animals, which are activated to produce disease by immunization with exogenous antigen. It is unclear why these T cells are not deleted during ontogeny in the thymus and, having escaped tolerance induction, why they are not spontaneously activated by self-antigen. To investigate these questions, we have examined an experimental model in which mice are tolerant to an antigen despite the presence of antigen-reactive T cells. We find that the T cells that escape tolerance induction are specific for minor determinants on the antigen. We propose that these T cells evade tolerance induction because some minor determinants are only available in relatively low amounts after in vivo processing of the whole antigen. For the same reason, these T cells are not normally activated but can be stimulated under special circumstances to circumvent tolerance.