Lack of T-cell tolerance of noninherited maternal HLA antigens in normal humans

Recent clinical reports of nonresponsiveness to noninherited maternal human leukocyte antigens have led to speculation that humans may acquire tolerance of noninherited maternal antigens through exposure to maternal cells neonatally or in utero. To test this hypothesis, we measured the responsiveness of normal subjects to their noninherited maternal and paternal antigens using cell-mediated lympholysis assays and mixed leukocyte reactions. All individuals exhibited cell-mediated lympholysis and mixed leukocyte reaction responses to the maternal cells that were comparable to those to the paternal cells. Limiting dilution analyses revealed significant cytotoxic T-lymphocyte precursor frequencies to both sets of parental antigens. To exlude the possibility that tolerance of individual noninherited maternal antigens was masked by the response to other antigens expressed on the same target cell, we raised cytotoxic T lymphocytes to the maternal cells and then tested for reactivity to a panel of targets that expressed single noninherited maternal HLA antigens. In all cases, each noninherited maternal antigen expressed on the maternal cells elicited a significant cell-mediated lympholysis response. An analysis of clinical data showed that pretransplant mixed lymphocyte reactions to maternal cells are not significantly lower than those to paternal cells. These data suggest that the reported B-cell tolerance of noninherited maternal antigens is not mediated by clonal deletion of T cells induced by exposure to the maternal cells neonatally or in utero.     

The T-cell repertoire is not dictated by self antigens alone.

The influence of genetic and environmental factors on the functional cytotoxic T cell (CTL) allorepertoire was studied by comparing the CTL precursor frequencies against the same HLA alloantigens in 116 sibling pairs. A significantly different precursor frequency was found in 68%, 61% and 59% of siblings sharing 0, 1 and 2 HLA haplotypes, respectively. These data show that, although HLA is important in determining the T-cell repertoire, this is hardly reflected in the allorepertoire. Even 50% of the monozygotic twin pairs showed a significant disparity in their CTL allorepertoire, indicating that environmental factors play a role as well. The non-inherited maternal HLA antigens could be identified as one of the environmental factors shaping the CTL allorepertoire.     

HLA antigens in patients with adult T-cell leukemia

HLA-A, B, C, and DR antigens were studied in Japanese patients with adult T-cell leukemia. No associations were found in comparisons with normal healthy controls.     

HLA antigens in sarcoidosis.

The HLA antigens were identified in sixty-five patients with sarcoidosis, comprising forty-five with uveitis, twelve with erythema nodosum and eight with arthritis. In the group with arthritis, B8 was present in seven of eight (P = 0-0016) and the haplotype 1,8 in five of eight (P = 0-0053). A1 was present in 44% with uveitis (P = 0-04). There was no other significant disturbance of antigen frequencies in uveitis or in erythema nodosum, but it was noteworthy that B27 was present in only two patients with uveitis.     

Analysis of the B-cell repertoire against antigens expressed by human neoplasms

Summary: The screening of tumor‐derived expression libraries for antigens detected by high‐titer immunoglobulin G antibodies from the sera of patients with cancer by SEREX (serological identification of antigens by recombinant expression cloning) allows a systematic search for antigens of human cancers. SEREX has led to the identification of a multitude of new tumor antigens in many different tumor entities. According to their specificities, the antigens can be grouped into different classes, of which the cancer testis antigens appear to be the most attractive candidates for vaccine development. Serologically defined human tumor antigens facilitate the identification of antigenic peptides recognized by tumor‐specific T lymphocytes, thus providing a molecular basis for polyvalent peptide‐based and gene‐therapeutic vaccine strategies in a wide variety of human neoplasms. Moreover, many of the SEREX‐identified antigens seem to play a functional role in the pathogenesis of malignant disease. With more than 2000 antigens listed in the SEREX database, it appears that tumor antigens that have resisted discovery to date are expressed in only a small minority of tumors, thus limiting their clinical usefulness. Novel strategies are necessary to identify antigens that can serve as a vaccine target in a broad spectrum of non‐Hodgkin's lymphoma patients.     

Primary cytotoxic T-cell response in vitro against Mls antigens in NZB-mice.

NZB-mice have a T cell hyperreactivity based on a primary response to minor histocompatibility antigens (MIH) on target cells identical to NZB on the H-2 complex (MHC). We tested the idea that a single MIH difference on MHC identical target cells is sufficient to elicit such a primary response in vitro. Cytotoxic T lymphocyte (CTL) response and activated T-helper cell (THC) frequencies were evaluated. NZB x CBA/J (Mls a/d) and NZB x CBA/Ca (Mls a/b) hybrids, which differ only at the M-locus, were raised. A primary cytotoxic response in the direction Mls b anti Mls d, but not vice versa was observed in vitro. In the assay used no unusual THC frequencies against Mls d could be demonstrated. The results favour cellular hyperreactivity in NZB which can be elicited by a single MIH antigen alone.     

Generation of the alpha beta T-cell repertoire.

The sequence of events leading to a diverse and competent alpha beta T-cell repertoire has been known in outline form for some time. Details continue to be sketched in, however, and some of these suggest previously unsuspected influences on repertoire content.     

Half of the T-cell repertoire combinatorial diversity is genetically determined in humans and humanized mice

In humanized mice, the T-cell repertoire is derived from genetically identical human progenitors in distinct animals. Thus, careful comparison of the T-cell repertoires of humanized mice with those of humans may reveal the contribution of genetic determinism on T-cell repertoire formation. Here, we performed a comprehensive assessment of the distribution of V-J combinations of the human β chain of the T-cell receptor (hTRBV) in NOD.SCID.γc(-/-) (NSG) humanized mice. We observed that numerous V-J combinations were equally distributed in the thymus and in the periphery of humanized mice compared with human references. A global analysis of the data, comparing repertoire perturbation indices in humanized NSG mice and unrelated human PBMCs, reveals that 50% of the hTRBV families significantly overlapped. Using multivariate ranking and bootstrap analyses, we found that 18% of all possible V-J combinations contributed close to 50% of the expressed diversity, with significant over-representation of BV5-J1.1+1.2 and BV6-J1.1+1.2 rearrangements. Finally, comparison of CD3(-) and CD3(+) thymocyte repertoires indicated that the observed V-J combination overlap was already present before TCR-MHC selection in the thymus. Altogether, our results show that half of the T-cell repertoire combinatorial diversity in humans is genetically determined.     

HLA antigens in pernicious anaemia.

The increased frequency of HLA-B7 alone and HLA-A3/B7 together, in the same patient, has been confirmed in pernicious anaemia. There is no increase prevalence of HLA-A3 alone. No association has been found between the presence of serum intrinsic factor type 1 antibody and HLA-A3 or HLA-B7.     

Ontogeny of cytotoxic T-cell repertoire modification.

The specificity of the residual anti-B10 cytotoxic T-cell response of B10. A mice rendered neonatally tolerant of B10 was compared to the anti-B10 response of adult and neonatal normal B10. A mice. The response of both spleen cells and thymus cells from adult and neonatal normal mice was biased toward Kb. This was in contrast to the response from tolerant spleen which was biased toward Db. The results suggest that the repertoire of normal mice is established neonatally and does not change radically without specific antigenic challenge. Furthermore the fact that the residual tolerogen specific cytotoxic T-cell precursors (pTc) in tolerant mice have a different repertoire to normal neonates makes it unlikely that they are remnants of a neonatal repertoire that developed prior to the full establishment of tolerance. Taking into account the present and previous results, the residual tolerogen-specific Tc in tolerant mice most likely represent a population of cells that has escaped tolerance induction due to their low avidity for antigen and provide the first evidence that avidity plays a role in tolerance among cytotoxic T cells.     

Antibody repertoire against culture filtrate antigens in wild house mice infected with Mycobacterium bovis BCG.

Wild house mice (Mus domesticus) captured in a Flemish pigsty were infected intravenously with 4 x 10(6) variable units of Mycobacterium bovis BCG and examined by Western blot analysis for IgG secretion against BCG culture filtrate (CF) antigens. Wild mice showed a marked individual variation in antibody pattern when tested 4, 6 and 8 weeks after infection. Some animals reacted to a wide range of antigens and others only to a limited number. Most wild mice recognized preferentially antigens with molecular weight of 24 kD, 32 kD, 37-38-40 kD, 65 kD and 82 kD, i.e. the major CF antigens known to be recognized by sera from BCG-infected inbred laboratory strains, BALB/c, DBA/2, CBA/Ca and C57BL/6. The 32-kD fibronectin-binding protein and the 65-kD heat-shock protein appeared as very immunodominant in wild mice. Furthermore, about 20-25% of the mice reacted strongly with a unique antigen of 35 kD estimated molecular weight, to which the tested inbred laboratory mice did not respond. Monitoring the size of the bacterial population in the spleen indicated that the BCG inoculum did not replicate in wild mice, suggesting that the Bcgr allele is expressed in this population.     

Characterization of the T-cell receptor Vbeta repertoire in the human immune response against Leishmania parasites

In order to explore a possible presence of hyperreactive T-cell clones in human cutaneous leishmaniasis (CL), we have investigated, by flow cytometry, the expression of Vbeta chains of T-cell receptors (TCRs) in the following types of cells: (i) peripheral blood mononuclear cells (PBMCs) from CL patients, which were then compared to those from normal volunteers; (ii) unstimulated and soluble Leishmania antigen-stimulated draining lymph node cells from CL patients; (iii) PBMCs from volunteers before versus after Leishmania immunization; and (iv) PBMCs from healthy volunteers that were primed in vitro with live Leishmania parasites. Our results show a modulation in the TCR Vbeta repertoire during CL and after antigen stimulation of patients' cells. Vaccination, however, leads to a broad expansion of different Vbeta TCRs. We also observed an association between TCR Vbeta12 expression, T-cell activation, and gamma interferon production upon in vitro priming with Leishmania. Collectively, these results both indicate that infection with live parasites or exposure to parasite antigen can modulate the TCR Vbeta repertoire and suggest that TCR Vbeta12 may be implicated in the response to Leishmania.     

T-cell enforced invariance of the antibody repertoire in the immune response against a bacterial carbohydrate antigen

The humoral response against the bacterial polysaccharide antigen alpha(1-->3) dextran (Dex) is controlled by J558 idiotype-(Id) specific T cells. These T cells of which the cell clone 178-4 Ts is a representative by all relevant criteria, recognize J558 Id-bearing B cells in an I-Ed-restricted manner. Costimulation via CD28/B7-1 but not via CD40/CD40L leads to T-cell activation. These T cells do not only suppress B cells producing the immunoglobulin (Ig)G3 isotype but also support the survival and clonal expansion of J558 Id positive B cells both in vivo and in vitro. This T-cell mediated dominance of the J558 idiotype limits the appearance of antibodies carrying other more diverse idiotypes which appear in immunized BALB/c nu/nu mice where no regulatory T cells occur. This T-cell mediated antibody invariance could be a strategy of the immune system responding to highly conserved antigens like polysaccharides, different from those against protein antigens, where diversity is assumed to be the basis for a successful response.     

HLA antigens in psoriasis

In the group (N = 136) of psoriatic patients 27 HLA antigens determined by A and B loci were identified. Phenotype, gene and haplotype frequencies were calculated and compared with the control data. A significant association between psoriasis and HLA-B13 and/or HLA-B17 was confirmed. The relative risk for these antigens amounted to 2.3 and 4.4 respectively. Among all haplotypes calculated for the psoriatic population there were only six with significant relative risk ranging from 3.1 to 27.4. Unexpectedly, the highest relative risk (27.4) was found for haplotype HLA-A9, X.     

HLA antigens in uveitis

HLA antigens are associated with a number of inflammatory eye diseases, most notably HLA B2 with anterior uveitis (AU). This association varies between different populations and ethnic groups. The aim of this study was to investigate the relationship between uveitis and HLA A, B and DR locus antigens in an Australian population. Seventy-two consecutive patients with uveitis were studied (37 males and 35 females) over a 6 month period. Thirty-two percent of the AU patients were HLA B27+, as were 42% of males (19% females) with their first attack of AU compared with 60% of males (23% females) with recurrent AU. The only significant difference in etiology between males and females was the greatly increased incidence of rheumatic diseases in males, in whom 77% (10/13) had radiological evidence of sacroiliitis. Additional findings included a lack of association between the HLA B7 cross reactive group and DR locus antigens in AU as well as the lack of any HLA associations in the 13 patients with posterior uveitis (PU).