The human T cell receptor repertoire utilized in response to HBsAg.

The complexity of the T cell receptor beta (TCRB) chain repertoire utilized in the recognition of recombinant hepatitis B surface antigen (HBsAg) was investigated. T cell lines were derived from two individuals vaccinated with Recombivax-HB and the TCRB repertoire was characterized by spectratype analysis, a molecular technology based on the differential size display of the complementarily determining region 3 (CDR3) of the TCRB chain. In contrast to the Gaussian distribution of CDR3 lengths observed for peripheral blood mononuclear cells (PBMCs), highly restricted patterns of CDR3 lengths were observed for most TCRB variable gene families in HBsAg-specific T cell lines (TCL). Although similarities in the repertoire of TCL derived from the two donors were noted, each TCL presented an unique profile of CDR3 length diversity. Among the TCR used by the two donors, no CDR3 sequence identity within or between TCRBV families was observed. Additionally, conservation of specific amino acids at homologous positions of the CDR3s was not evident. The T cell repertoire in response to HBsAg is oligoclonal, involves multiple TCRBV families and is individually specific.

Defect in Th1-like cells of nonresponders to hepatitis B vaccine.

Peripheral blood lymphocytes from nonresponders to hepatitis B vaccine (HBsAg) failed to undergo a proliferative response to recombinant HBsAg in vitro, whereas cells from responders proliferated vigorously. The lack of proliferative response was not due to defective antigen presentation in that MHC-identical responder and nonresponder antigen presenting cells were equally effective in stimulating responder T cells. Nonresponder T cells did not proliferate in response to antigen-pulsed MHC identical responder antigen presenting cells. The present study demonstrated that: 1) there were no detectable (1 in < 20 x 10(4) HBsAg-precursor T cells in any of the nonresponders, while in responders the frequency of HBsAg-precursor T cells ranged from 1 in 3.2 x 10(3) to 1 in 40 x 10(3); 2) nonresponder cell cultures did not secrete IL-2 in response to HBsAg stimulation; 3) exogenous recombinant IL-2 did not restore the proliferative response of the T cells in HBsAg-pulsed cultures of nonresponders. These results suggest that the cellular basis for the lack of response to HBsAg is a defect in HBsAg-specific Th1-like cells; either there is an absence of the Th1 cells or cells with TCR specificity for HBsAg are present but are unresponsive to the HBsAg peptide-MHC complex (i.e., anergy or tolerance).

Mitogens, superantigens, and nominal antigens elicit distinctive patterns of TCRB CDR3 diversity.

The third complementarity-determining region (CDR3) is the only nongermline-encoded hypervariable region of the T cell receptor beta (TCRB) chain, and it is the region that has been predicted to confer fine specificity of the TCR for peptide-MHC complexes. For this reason analysis of TCRB CDR3 heterogeneity may provide insight into immune mechanisms operative in infectious and autoimmune diseases. PBMC stimulated with either mitogen (PHA), superantigen (TSST-1), or nominal antigen (tetanus toxoid) have been compared with unstimulated PBMC using a two-dimensional approach. Analysis of the expressed TCRBV gene repertoire CDR3 length profile coupled with SSCP methodology enabled the discrimination of sequences with the same CDR3 length. For both freshly isolated and PHA stimulated PBMC, a normally distributed spectrum of CDR3 lengths (five or more products) was observed. These products differed by 3 bp (1 amino acid) due to the strict requirement for in-frame rearrangements in the CDR3 region of TCR. By contrast, tetanus toxoid stimulated PBMC had restricted profiles for most TCRBV families after as few as 7 days of incubation. The oligoclonal nature of samples showing CDR3 length restriction was revealed by SSCP analysis and confirmed by sequence determination. Superantigen stimulation resulted in unique patterns of diversity, which included polyclonal expansion of specific TCRBV families as well as oligoclonal expansion of most other TCRBV families. These data reveal complex yet distinct patterns of TCR diversity in response to different T cell activation stimuli.

TCRBV12 genes are polymorphic but the protein products encoded by each gene are conserved.

The human TCRBV gene complex contains three BV12 genes and all are polymorphic. There are two alleles of BV12S4; one allele contains a stop codon in the coding region which precludes its expression. There are four alleles of BV12S2 and two alleles of BV12S3 genes; however, the substitutions present in both genes are conservative. Although allelic variants exist for each of the three BV12 genes, only one protein product is encoded by each gene.

Normal HBsAg presentation and T-cell defect in the immune response of nonresponders.

Lymphocytes from nonresponders to HBsAg fail to proliferate in vitro in the presence of HBsAg-pulsed antigen presenting cells. We studied four pairs of major histocompatibility complex (MHC)-matched, mixed lymphocyte reaction-negative individuals discordant for HBsAg response. For each pair, responder lymphocytes proliferated in the presence of nonresponder antigen-pulsed antigen presenting cells. Responder and nonresponder antigen presenting cells were equally effective. There was no evidence for inhibition of responder T-cell proliferation by nonresponder lymphocytes or antigen presenting cells. The defect is thus in the helper T cells of nonresponders and not in the antigen processing or binding of processed peptides to MHC molecules on antigen presenting cells.

Genetic control of the decline of natural killer cell activity in aging mice.

NK cell activity declines with age and is strain dependent. We investigated the age associated decline of NK cell activity in the HW26C strain of mice. The bilineal congenic strain HW26C which contains a segment of chromosome 4 of BALB/cBy introduced onto the C57BL/6By (B6) background was used to investigate the decline of NK cell activity with age. Our experiments showed that there is a significant decline of NK cell activity in old (18-26 months) HW26C mice as compared to the B6. By contrast, the NK cell frequency determined using a surface marker for NK cells, NK1.1, did not show any significant difference with age. It appears therefore, that the decline in NK activity during aging is a reflection of loss of lytic activity rather than an actual decline in the number of NK cells and the responsible gene(s) resides in chromosome 4.

Cellular recognition and HLA restriction of a midsequence HBsAg peptide in hepatitis B vaccinated individuals.

Vaccination with native HBsAg results in both a humoral and a cellular immune response in humans. In individuals who responded to vaccination, the HBsAg (S region) specific response, as measured by cell proliferation, diminished significantly after 12 weeks, a time when the antibody response was still vigorous. Reduced and nonreduced HBsAg were equivalent in eliciting lymphocyte proliferation. Anti-MHC class II monoclonal antibodies were used in blocking studies to demonstrate that anti-HLA-DR but not anti-HLA-DQ or anti-HLA-DP inhibited specific lymphocyte proliferation to HBsAg. Both the monomer (reduced) and dimer (nonreduced) forms of an immunodominant midsequence HBsAg peptide (amino acid residues 139-146) produced lymphocyte proliferation roughly comparable to that induced by whole HBsAg in 6 of 7 responders immunized with whole HBsAg and the peptide-induced proliferation was blocked by anti-HLA-DR but not by anti-HLA-DP antibodies. These results suggest that HBsAg p 139-146 is a major immunodominant peptide of HBsAg and is restricted by HLA-DR.

Functional deficiency of antigen-presenting cells in the synovial fluid of rheumatoid arthritis.

In our study of rheumatoid arthritis (RA) patients, we observed a decrease of tetanus toxoid antigen-presenting capacity of synovial fluid (SF) adherent cells to autologous T cells of either SF or peripheral blood. Additionally, we found a higher capacity of adherent synovial cells to stimulate autologous T-lymphocytes. Our results suggest that antigen-presenting cells of the SF of RA patients have defects that may play a role in defective presentation of antigens in joints and may account for other abnormal functions important in the pathogenesis of RA.