Antigen-specific T cell clones restricted by DR, DRw53 (MT), or DP (SB) Class II HLA molecules. Inhibition studies with monoclonal HLA-specific antibodies

Autoreactive T cells from a type I diabetic recognize multiple class II products

Mononuclear cells obtained from a child at the acute presentation of type I diabetes were stimulated in vitro with human insulin followed by IL-2 and IL-4. All of the T-cell clones isolated from this stimulation were autoreactive, recognizing autologous B cells in the absence of insulin or other exogenous antigens. Eleven CD4+ clones were studied in detail to identify the class II MHC antigens stimulating these autoreactive cells. The donor was heterozygous for DR3DQw2 and DR4DQw3.2 haplotypes, a combination of alleles with a greatly increased risk for type I diabetes. The clones demonstrated skewed recognition of class II antigens. Three clones appeared to recognize a peptide derived from one class II beta chain (DR beta 1, DR4Dw4) presented by another class II beta chain (DR beta 4, DRw53). Three clones were stimulated by cells expressing DPw4 molecules. Only one clone recognized a product derived from the DR3 haplotype. In contrast to both antigen-specific and autoreactive T-cell clones derived from normal individuals, many of the autoreactive T cells isolated from this subject were stimulated by class II molecules other than DR beta 1. The results support the hypothesis that autoreactive T cells recognize autologous peptides in association with MHC and some of these peptides are derived from self MHC molecules.

Identification of cross-reactive T cell restriction epitopes located on the DR7 beta 1 and DR beta 4 molecules

L cell fibroblasts transfected with HLA class II cDNA clones isolated from a cDNA library produced from a DR7 homozygous cell line were used as antigen-presenting cells (APC) for three HLA DR-restricted, diphtheria toxoid-specific T-cell clones in order to assess the antigen-presenting ability of the transfectants and to define the class II restriction of each clone. Class II-expressing transfectants are capable of presenting antigen to antigen-specific T-cell clones, although the transfectants are less efficient at antigen presentation than conventional APC. Paraformaldehyde fixation of transfectants prior to antigen pulsing abrogated antigen presentation, demonstrating that the transfectants require antigen processing. Antigen presentation by transfectants is completely inhibited by CD4-specific monoclonal antibodies (mAb) and one of four DR-specific mAb, whereas antigen presentation by conventional APC is only partially inhibited. Both the DR alpha:DR7 beta 1 and DR alpha:DR beta 4 (DR omega 53) molecules of the DR7 allotype serve as restriction elements for the diphtheria toxoid-specific T-cell clones. One clone is restricted by the DR7 beta 1 molecule, another clone by the DR beta 4(DR omega 53) molecule, and a third clone by a cross-reactive T cell epitope on DR7 beta 1 and DR beta 4(DR omega 53) molecules. The two DR beta 4(DR omega 53)-restricted clones react, however, differently with a panel of HLA-DR DR omega 53-positive human peripheral blood lymphocytes used as APC. Therefore the data presented here clearly document that the DR beta 4 (DR omega 53) chain may serve as restriction elements for DT-specific T-cell clones. They also provide the first evidence for functional cross-reactivity of the products of two different DR beta loci and in addition emphasize the high complexity of the supertypic HLA-DR omega 53 specificity.

Functional polymorphism of each of the two HLA-DR beta chain loci demonstrated with antigen-specific DR3- and DRw52-restricted T cell clones

HLA-DR3- and HLA-DRw52-associated functional polymorphism was investigated with selected tetanus toxoid (TT)-specific T cell clones. We have shown earlier that HLA-DR antigens are encoded by two distinct loci, DR beta I and DR beta III. The alloantigenic determinant(s) defined by the serological HLA-DR3 specificity map to the former, while the supratypic HLA-DRw52 determinants map to DR beta III. Furthermore, we have recently recognized by DNA sequencing three alleles of HLA-DRw52 at locus DR beta III, referred to as 52 a, b, and c. Our objective was to correlate the pattern of T cell restriction with the gene products of individual DR beta chain loci and with the three newly described alleles of locus DR beta III. Among the selected T cell clones, 5 reacted exclusively when TT was presented by HLA-DR3+ APCs (TT-DR3-APC). In contrast, two T cell clones were stimulated by TT-DRw52-APC. More specifically, these two T cell clones (Clones 10 and 16) were stimulated by different subsets of TT-DRw52-APC. Clone 16 responded to some DR3 and TT-DRw6-APC, while clone 10 was stimulated by other TT-DR3 and TT-DRw6, and all TT-DR5-APC. This same pattern of DRw52 restriction was found in panel, as well as in family studies. Because this suggested a correlation with the pattern of DRw52 polymorphism observed earlier by DNA sequencing and oligonucleotide hybridization, the APC used in these experiments were typed for the 52 a, b, and c alleles of locus DR beta III by allele-specific oligonucleotide probes. This distribution overlapped exactly with the stimulation pattern defined by the T cell clones. Clone 16 responded to TT-52a-APC, clone 10 to TT-52b-APC, and both clones to a TT-52c-APC. The response of the T cell clones was inhibited differentially by mAbs to DR. Raising TT concentration, or increasing HLA-class II expression with INF-gamma both affected the magnitude of response of the TT-specific clones but did not modify their specificities. These results demonstrate that a restriction specificity can be attributed to the DR beta III locus and illustrate the functional relevance of the polymorphism observed at this locus. This is of special interest in view of the striking difference in the pattern of structural diversity among alleles of DR beta I and DR beta III.

Major histocompatibility complex (MHC) restricted antigen recognition: high frequency of human T-cell clones recognizing novel MHC class II determinants

We have used antigen-specific human T-cell clones to study the relationship between MHC and antigen recognition specificities expressed by T cells. Tetanus toxoid (TT)-specific T-lymphocyte clones were derived from a immunized HLA-DR2,7 heterozygous donor by limiting dilution from peripheral blood mononuclear cells (PBM) restimulated with TT in vitro. Clones were screened for MHC-restricted antigen recognition against antigen-presenting cells (APC) from a panel of HLA-typed donors, using an in vitro T-cell proliferation assay. Several distinct patterns of antigen recognition were identified. In addition to T cells that recognized TT in association with donor class II MHC antigens, we found clones that simultaneously expressed self-restricted antigen recognition and alloreactivity, and clones with specificity for antigen in the context of MHC antigens not expressed by the T-cell donor. This was confirmed in inhibition studies using well-characterized monoclonal antibodies against class II MHC antigens to block specific proliferative responses. We propose a possible structure for the determinant recognized by two of the clones. These results suggest that the T-cell antigen receptor undergoes random or antigen-dependent changes in vitro, and that this may be a mechanism for somatic diversification of the T-cell repertoire.

Trinitrophenyl reactive T-cell clones in functional and molecular analysis of the HLA-D region

We believe that the approach we have utilized contributes to more complete understanding of the role of HLA class II molecules in presentation of antigen to T lymphocytes and helps to resolve paradoxes presented by earlier studies in which class II-associated restrictions were not apparent. The approach has depended upon development of a library of cloned TCL reactive to a particular haptenic determinant in various class II MHC contexts. It employed initial screening for MHC restriction by analysis on allogeneic stimulator cell panels that could be confirmed or clarified by antibody blocking experiments employing mAb of defined specificities. This has led to clear identification of TCL restricted to recognition of TNP in the context of each of the major class II molecular species, DR, DQ and DP. It has also raised the intriguing and novel possibility that in some instances, at least for DP, T-cells may employ restricting elements, as revealed by mAb blocking, that are either nonpolymorphic or of very low polymorphism. Finally, where important functional polymorphisms have been identified at apparent variance from defined serological specificities, it has been possible to correlate antigen recognition with molecular polymorphisms defined at both the protein level, by amino acid sequencing, and the genomic level by restriction enzyme polymorphisms. As these approaches are combined with new molecular genetic techniques for generation of novel class II constructs, it seems likely that important, but as yet unresolved, questions relating to the nature of the ternary complex involving antigen, MHC molecule and T-cell receptor will be resolved.

Molecular localization and polymorphism of HLA class II restriction determinants defined by Mycobacterium leprae-reactive helper T cell clones from leprosy patients

MHC class II molecules carry the restriction determinants (RDs) for antigen presentation to antigen-specific Th lymphocytes. This restriction of T cell activation endows those molecules with a key role in the induction and regulation of antigen-specific immune responses. Moreover, class II molecules are the products of class II immune response (Ir) genes. The polymorphism of these Ir genes leads to genetically controlled differences in immuneresponsiveness between different individuals. An important human example is leprosy, in which HLA class II-linked Ir genes determine the immune response against Mycobacterium leprae, the causative organism of the disease. Since the immune response against M. leprae is entirely dependent on Th cells, the HLA class II-linked Ir gene products may well regulate the immune response by controlling the presentation of M. leprae antigens to Th cells. We therefore have investigated the HLA class II RD repertoire of M. leprae-reactive Th cell clones (TLC) by means of extensive panel and inhibition studies with fully class II-typed allogeneic APCs and well-defined HLA class II-specific mAbs. The TLC studied (n, 36) proliferated specifically towards M. leprae, produced IFN-gamma upon activation, and had the CD3+CD4+CD8- phenotype. The results show in the first place that the majority of the RDs for M. leprae reside on DR and not on DP or DQ molecules. This indicates a major role for DR molecules in the immune response to M. leprae and suggests that these molecules are the main products of M. leprae-specific Ir genes. Furthermore, since the expression of DR molecules is much stronger than that of DP and DQ molecules, these findings suggest that the localization of RDs for M. leprae on class II molecules correlates with the quantitative expression of these molecules. The observation that the RDs on DR molecules coded by a DR4 haplotype were situated only on those DR molecules that are known to be highest in expression can be explained in the same way. Second, four distinct RDs related with but not identical to the Dw13 allodeterminant were carried by the DR+DRw53- (alpha beta 1) molecules of a DR4Dw13 haplotype. Since the known amino acid residue differences between the allelic DR4 related Dw beta 1 chains cannot explain the observed RD-polymorphism, this observation suggests that multiple distinct RDs unique for the DR4Dw13 haplotype are expressed by these molecules. Only 2 of 36 TLC were not restricted by DR.(ABSTRACT TRUNCATED AT 400 WORDS)

Functional roles of human class II antigens in T cell proliferative response. Comparison of the DR and DQ molecules using mouse monoclonal antibodies

The monoclonal antibody (mAb) NC1 recognizing a monomorphic DR determinant and the anti-DQ mAbs PLM2, PLM9, and PLM12 recognizing polymorphic DQ determinants were produced. NC1 reacted with the H1L1 (DR) and H1L2(DRw52, DRw53 and allelic products) complexes of a DR family, while the specificity of PLM12 was DQw3 (previously called TB21). Both PLM2 and PLM9 reacted with the allodeterminant of TA10 (a subtype of DQw3). These three mAbs immunoprecipitated the same H2L3 complex of a DQ family. With the aid of these mAbs, DR molecules but not DQw3 molecules were detected on monocytes in significant quantities. The functional roles of these class II molecules in the T cell proliferative responses to three soluble antigens (PPD, mite, Candida) and alloantigens were examined by blocking assays in vitro. NC1 almost completely inhibited T cell proliferative responses against both soluble antigens and allogeneic antigens. In contrast, PLM2, PLM9 and PLM12 showed no significant inhibitory effects at all. These results indicate that DR and DQ antigens are different in their functional roles as well as their serological and immunochemical characteristics and tissue distributions; these three soluble antigens and the alloantigen were presented in association with determinants residing predominantly on two forms of NC1-reactive molecule, namely the H1L1 and/or H1L2 complex of a DR family but not in association with the DQw3 allodeterminant on the H2L3 complex of a DQ family.

Comparison of HLA-Dw1 and -Dw2 positive adherent cells in antigen presentation to heterozygous T-cell lines: a low rubella antigen-specific response associated with HLA-Dw2

T-cell lines specific for purified tuberculin (PPD), rubella, and herpes simplex virus (HSV) antigens were established from two Dw1/w2 heterozygous subjects. Fresh peripheral blood monocytes from healthy individuals with shared and non-shared D-antigens were used as presenting cells and the T-cell lines as responders in lymphocyte blast transformation assays with specific antigens. An HLA-restricted reaction was seen with all the antigens, although the PPD- and HSV-specific cell lines reacted stronger than rubella-specific lines when the specific antigens were presented by monocytes not sharing the D-antigens. A significantly lower response was seen when rubella antigen was presented by Dw2 positive monocytes as compared to response promoted by Dw1 positive monocytes (p less than 0.0001, Mann-Whitney U-test), whereas no such difference was seen in responses to PPD or herpes simplex antigen.

Molecular characterization of a subtype of DQw1 recognized by hapten-specific T cells

Previous studies of HLA-restricted antigen recognition by cloned T cells have frequently demonstrated reactivity that did not correlate precisely with the expression of serologically defined HLA specificities. To further explore such discrepancies, we utilized monoclonal antibody (MoAb) blocking, partial NH2-terminal amino acid sequencing, and Southern blot hybridization techniques to analyze the fine specificity of four autologous trinitrophenyl-specific T cell lines restricted to DR2-linked epitopes. MoAb blocking studies demonstrated that two of these lines recognized determinants on DR molecules while the other two recognized determinants on the same molecule that expresses the DQw1 determinant. However, these latter two lines appeared to recognize a DQw1-related determinant found primarily in association with DR2, but not the other DQw1-associated DR alleles, DR1 and DRw6. To ascertain whether these lines were defining a functional split of DQw1, we performed partial NH2-terminal amino acid sequencing of the molecules precipitated with a DQw1-specific MoAb (Genox 3.53) from different stimulator lines. The results showed that these T cell lines recognized a subtype of DQw1 that is in linkage disequilibrium with DR2. Moreover, we identified characteristic restriction fragment length polymorphisms with a DQ beta-specific cDNA that correlated with stimulatory capacity for the DQw1-restricted lines. These results demonstrate that: DQ molecules may provide restriction determinants that are incorrectly assigned to DR molecules on stimulator panel analyses; cloned antigen-specific T cell lines recognize polymorphic regions of class II molecules not distinguished by either conventional typing antisera or xenogeneic MoAb; and the DQw1 epitope(s) is located on a heterogeneous group of DQ molecules that differ from each other in the primary sequence of their beta chains.

Restriction of the in vitro anti-mannan antibody response by HLA-DQ molecules

In humans, the in vitro antibody response directed towards mannan, a polysaccharide extracted from the cell wall of Candida albicans, has been previously shown to be dependent on the presence of T lymphocytes and monocytes. Evidence is now given for the existence of a genetic restriction governing this response since antibody production is achieved provided that monocytes and T lymphocytes on one side and monocytes and B lymphocytes on the other side are of the same origin. In order to delineate the restriction element governing these interactions, blocking experiments have been designed using well-defined monoclonal antibody, anti-HLA class II molecules. The results clearly indicate that the restriction element belongs to the HLA-DQ molecular series, as shown in T-cell proliferation and antibody production assays in the presence of either T cells or T-cell supernatants. Incubation of isolated cell populations (T, B lymphocytes and monocytes) with the monoclonal antibody have indicated that DQ determinants are involved in the mannan presentation by monocytes to T and B cells. The HLA-DQ mediated restriction of the in vitro immune response to mannan has been observed in all the subjects tested, suggesting that mannan epitopes are preferentially, or even only, recognized in association with an unique group of HLA-class II molecules, namely HLA-DQ.

Quantitative and qualitative differences in HLA-DR molecules correlated with antigen-presentation capacity

The monoclonal antibodies 7.3.19.1 (anti-DRw52-like) and B8.11.2 (anti-DR framework) were used for the isolation and characterization of HLA class II molecules expressed by HLA-DR3 and DR5 homozygous B cell lines. Sequential immunoprecipitation studies demonstrated that from these cells class II molecules can be isolated which are characterized by the presence or absence of DR framework (DR) and DRw52-like (DRw62) determinants: (DR+, DRw52+), (DR+, DRw52-) and (DR-, DRw52+). The DR3 donor cells appeared to express only the (DR+, DRw52+) and (DR-, DRw52+) class II molecules whereas DR5-positive cells express only the (DR+, DRw52+) and (DR+, DRw52-) class II molecules. Besides qualitative differences some of the above-mentioned molecules appeared to differ in their levels of expression. To investigate whether this might have functional implications, cells with the HLA-DR3 and -5 haplotypes were used to present antigen purified protein derivative of tuberculin (PPD) to PPD-specific T cell lines and the blocking capacity of the two monoclonal antibodies 7.3.19.1 and B8.11.2 was determined. A remarkable correlation was observed between the type of class II molecule blocked by these monoclonal antibodies and its quantitative expression. However, (DR-, DRw52+) molecules, clearly expressed by DR3 cells, were not involved in the presentation of PPD. This indicates that not only quantitative but also qualitative aspects may play a role in the selection of the type of class II molecule that will be involved in antigen presentation.

HLA control of the proliferative T lymphocyte response to antigenic determinants on mumps virus. Studies of healthy individuals and patients with type 1 diabetes

The proliferative T lymphocyte responses to two different mumps antigen preparations, S (nucleocapsid) and V (viral envelope), were characterized. Eight patients with Type 1 (insulin-dependent) diabetes mellitus were all found to be responders to S and V mumps antigen. Among the 64 healthy individuals, 52 were classified as responders to the S antigen and 50 responders to the V antigen. No difference was found between T lymphocytes from Type 1 diabetic patients and those from healthy individuals as regards the effect of indomethacin on the mumps-specific response. The majority of the mumps-specific T lymphocytes seemed to be restricted by epitopes on the HLA-DR molecules. The frequency of mumps antigen-reactive T lymphocytes (ARTL) was found to be low when the response was restricted by DR3-associated elements, and high when it was restricted by DR4-associated elements, compared to the frequency of ARTL when other DR-associated elements restricted the mumps-specific response. For the majority of the individuals tested, the DR-associated hypo- and hyper-responsiveness was found with both the S and the V mumps antigens.

Class II determinants recognized by TNP-specific cloned human T cell lines

Cloned human T lymphocyte lines were generated against trinitrophenyl (TNP)-modified autologous cells from four different individuals. By examining the reactivity patterns of 58 of these T cell clones (TLC) on panels of HLA-typed antigen presenting cells and employing monoclonal antibodies (MoAb) for inhibition studies, we have demonstrated that TNP may be recognized in the context of different DR and DP associated determinants. We did not identify any TLC restricted by determinants associated uniquely with DQ. Determinants associated with the expression of DR1,2,4,5, and 7 as well as the supertypic specificities DRw52 (MT2) and DRw53 (MT3) functioned as restriction elements. In addition, at least two antigenically distinct regions of the DP4 molecule appeared to function in the presentation of TNP. One TNP-specific TLC recognized a determinant associated with the expression of DP4 while another recognized TNP in the context of a highly nonpolymorphic determinant on DP which was expressed on all stimulators tested. Monoclonal antibody blocking studies suggest that these two determinants lie on different portions of the DP molecule. These studies demonstrated that both polymorphic and relatively nonpolymorphic restriction determinants on DR and DP may function in the presentation of conventional antigen to autologous lymphocytes.

Identification, at the genomic level, of an HLA-DR restriction element for cloned antigen-specific T4 cells

Two T4 cell clones (TLC) specific for antigenic epitopes on Chlamydia trachomatis were studied. Using a panel of allogeneic antigen-presenting cells (APC), both TLC were found to be restricted by HLA class II elements closely associated with, but not identical to the DRw5S specificity, as determined by highly selected alloantisera, a monoclonal antibody (mAb), 109d6, and confirmed on the DNA level by determination of restriction fragment length polymorphisms (RFLP) with a DR beta probe. Furthermore, HLA-DR-specific mAb, including 109d6, but not other HLA class II- or class I-specific antibodies inhibited the two TLC, strongly suggesting that the restriction element is expressed by a DR molecule. Using digestion with Hind III restriction enzyme and a DR beta probe, we found a complete concordance between the appearance of a 9.3 kilobase band and the ability of allogeneic APC to restimulate the T cell clones. Thus, the restriction element for these T cell clones appear to be expressed by DR molecules, but can, at present, only be detected at the genomic level.

Strong association of rheumatoid arthritis with the presence of a polymorphic Ia epitope defined by a monoclonal antibody: comparison with the allodeterminant DR4

Among individuals with rheumatoid arthritis the presence of the polymorphic Ia antigen epitope detected by the monoclonal antibody 109d6 is more strongly correlated with disease susceptibility than are other specificities, such as HLA DR4, DRw53 (MT3) or the antigenic determinant, defined by the monoclonal antibody 17-3-3S. The cells of 93% of Caucasian and Hispanic patients react with the 109d6 reagent. As was the case in normal individuals, all DR4-positive patients express the 109d6 determinant; however, 26% of those with rheumatoid arthritis have the epitope recognized by antibody 109d6, but lack the specificity DR4. Of these, one-third expresses only HLA DR1 and DQw1 (MT1, MB1) determinants. Studies of family members reveal that here the determinants 109d6, DR1, and DQw1 are encoded by the same unusual haplotype. In certain other individuals with rheumatoid arthritis who express DR4, DRw53, and the 109d6 determinants, family studies show that the 109d6 epitope is encoded not only by the haplotype specifying DR4 but also by the opposite haplotype that does not bear the genes for DR4. This suggests that homozygosity for certain Ia epitopes is relevant to determining the disease-susceptibility state. These studies emphasize the utility of monoclonal antibodies as reagents for the recognition of Ia epitopes that are more closely involved in the determination of disease susceptibility than are allomorphic molecules detected by conventional typing alloantisera.