Molecular analysis of HLA-DRB1, -DQA1 and -DQB1 polymorphism in Turkey

We report the evaluation of MHC class II polymorphism in the population of Turkey. HLA-DRB1, -DQA1 and -DQB1 have been investigated by polymerase chain reaction and sequence-specific oligonucleotide probe hybridisations (PCR/SSO) and sequence-specific priming (SSP) in 250 randomly selected healthy individuals. We also report the allelic distribution of these genes. The most frequent alleles detected were DRB1*1101 (0.104), *0301 (0.092), *0701 (0.090), DQA1*0501 (0.334), *0102 (0.164) and *03 (0.148) and DQB1*0301 (0.256), *02 (0.164), *0302 (0.128). The frequent 'putative' three-locus haplotypes carry the most frequent alleles at these loci. The most frequently detected class II "haplotypes" are DRB1*1101 DQA1*0501 DQB1*0301 (0.100), DRB1*0301 DQA1*0501 DQB1*02 (0.092) and DRB1*0701 DQA1*0201 DQB1*02 (0.072). The distribution of alleles and 'putative' haplotypes has shown common features with other Mediterranean populations. The results extend the HLA map to another Mediterranean country and provide a database for further HLA-disease association studies and transplantation applications.

In vitro expansion of T-cell-receptor Valpha2.3(+) CD4(+) T lymphocytes in HLA-DR17(3), DQ2(+) individuals upon stimulation with Mycobacterium tuberculosis

The T-cell receptor (TCR) Valpha/beta gene product expression upon in vitro stimulation with mycobacteria was investigated to assess whether T-cell proliferation was associated with any specific TCR V gene usage. T-cell-enriched populations from peripheral blood of Mycobacterium bovis BCG-vaccinated healthy blood donors were stimulated in vitro with live or killed M. tuberculosis or with a soluble extract thereof. TCR Valpha/beta repertoire analysis of reactive CD4(+) and CD8(+) T cells revealed a selective HLA-DR17(3), DQ2-restricted expansion of Valpha2.3(+) CD4(+) T cells upon stimulation with live M. tuberculosis or its soluble extract. Third-complementarity-determining-region (CDR3) length analysis of the expanded Valpha2.3(+) T cells indicated an oligoclonal pattern with short CDR3 lengths in six of seven HLA-DR17(3), DQ2(+) individuals tested. In addition, Valpha/Vbeta repertoire analysis of T lymphocytes from a DR17(3), DQ2(+) donor before and after BCG vaccination revealed that positivity of skin test reactivity was associated with expansion of Valpha2.3(+) CD4(+) T lymphocytes with preferential use of a short CDR3 peak length after in vitro stimulation. Separation of M. tuberculosis soluble extract by fast protein liquid chromatography (FPLC) purification indicated that fractions corresponding to molecular masses of 60 to 70 and 15 to 25 kDa were particularly effective in eliciting Valpha2.3(+) CD4(+) T-cell expansion.

Shared epitope homozygosity' is strongly associated with rheumatoid arthritis in Turkey. Istanbul Rheumatology Study Group

OBJECTIVE

Associations with HLA-DRB alleles, implicated in the aetiopathogenesis of rheumatoid arthritis (RA), are found to be different in various ethnic groups. This study aimed to investigate DRB1 alleles in RA patients in Turkey.

METHODS

The DRB region of the MHC was screened by polymerase chain reaction/sequence-specific oligonucleotide (PCR/SSO) hybridizations in 101 seropositive RA patients and compared with 101 healthy controls.

RESULTS

Significant differences were in the frequencies of DRB1*0404 (12 vs 1, P = 0.003, OR = 13.5), *0401 (19 vs 4, P = 0.001, OR = 5.6) and *0408 (5 vs 0, P = 0.06, OR = 11.6) between RA patients and controls. The shared epitope (SE) was present in 70.2% of RA patients compared to 31.6% of controls (P < 0.0001, OR = 5.1). A double dose of SE was considerably more frequent in the RA group (21 vs 1, P < 0.0001, OR = 26.5).

CONCLUSION

These results support the reported positive association of RA with SE in seropositive patients in Turkey, and emphasize 'SE homozygosity' as the most strongly associated genetic susceptibility marker for RA.

The distribution of HLA-DRB alleles in ulcerative colitis patients in Turkey

Recently described distinct associations of HLA class II genes with ulcerative colitis (UC) suggest a genetic heterogeneity for disease susceptibility. In this study, HLA-DRB alleles of UC patients (n = 59) from Turkey were investigated and compared with healthy controls (n = 244). Using molecular genotyping by polymerase chain reaction (PCR) and sequence-specific oligonucleotide hybridization, we have shown a positive association of UC patients with the HLA-DRB1*1502 allele (10/59 vs. 16/244; P = 0.02; OR: 2.9) and a negative association with the DRB1*13 allele (7/59 vs. 64/244; P = 0.03; OR: 0.38) compared to controls. HLA-DRB1*0701 was significantly increased in perinuclear antineutrophil cytoplasmic antibody (pANCA)-positive UC patients compared to pANCA-negative patients (8/32 vs. 0/27; P = 0.005), whereas DRB1*1502 was observed more frequently in pANCA-negative patients (8/27 vs. 2/32; P = 0.03). These results extended the reported positive association of DRB1*1502 with UC to another population and supported the genetic susceptibility associated with HLA genes for disease development.

Humoral immune response to mycobacterial heat shock protein (hsp)65 in the cerebrospinal fluid of neuro-Behçet patients

Although systemic immune reactivity to 65-kD mycobacterial hsp65 (m-hsp65) has been shown previously in Behçet's disease (BD), local immune response was not investigated. We studied anti-m-hsp65 IgG, IgM and IgA antibodies in the serum and cerebrospinal fluid (CSF) of 25 BD patients with cerebral parenchymal involvement (p-NBD), seven BD patients with intracranial hypertension (ih-NBD), eight BD patients without central nervous system (CNS) involvement, 30 patients with multiple sclerosis (MS) and 24 patients with non-inflammatory CNS disorders (NIC). Significantly higher CSF IgG responses were detected in p-NBD patients (ELISA ratio 1.3 +/- 0.9) compared with NIC (0.7 +/- 0.4, P < 0.01). In p-NBD patients' IgG, IgM or IgA CSF anti-m-hsp65 positivity rate was 48% (12/25); this was significantly higher when compared with MS (3/30; P < 0.03) and NIC (3/24; P < 0.01). CSF anti-m-hsp65 IgG ratios correlated with the duration of BD (r = 0.4, P < 0.04) but not with the duration of neurological involvement. Serum IgM and IgA responses were elevated in ih-NBD, suggesting a different type of involvement than p-NBD. These results implicate an increased local humoral response to m-hsp65 in the CSF of p-NBD patients, which might be related to the pathogenesis of neurological involvement.

HLA-DR and -DQ associations with multiple sclerosis in Turkey

The DRB, DQA, and DQB subregions of the major histocompatibility complex (MHC) were investigated by polymerase chain reaction and sequence-specific oligonucleotide probe hybridization (PCR/SSO) in 103 multiple sclerosis (MS) patients and 101 healthy controls from Turkey. Significant differences were detected between MS and control populations in the frequencies of DRB1*1501 [29 vs. 14, p = 0.02, odds ratio (OR) = 2.4], DRB1*04 (35 vs. 18, p = 0.01, OR = 2.3), DQB1*0302 (30 vs. 15, p = 0.02, OR = 2.3), DQB1*0602 (27 vs. 10, p = 0.005, OR = 3.2), DQB1*0501 (10 vs. 24, p = 0.01, OR = 0.3), DQA1*0101 (16 vs. 31, p = 0.02, OR = 0.4), and DQA1*0103 (7 vs. 19, p = 0.02, OR = 0.3). These results confirm the proposed positive association of the Dw2 (DRB1*1501 DQA1*0102 DQB1*0602) haplotype with MS in Caucasians in our Turkish population (25 vs. 8, p = 0.003, OR = 3.7). Furthermore, the "putative" haplotype supposed to be more frequent in the MS population of Mediterranean countries, namely DRB1*04 DQA1*03 DQB1*0302, is also associated with MS in Turkey (29 vs. 12, p = 0.006, OR = 2.9). The presence of two different haplotypic associations in MS emphasizes the complexity of the genetic susceptibility to MS in different populations.

Paroxysmal dysarthria and ataxia in a patient with Behçet's disease

The paroxysmal attacks which are frequently encountered in the course of multiple sclerosis (MS) are characterised by their sudden onset, short duration and frequent repetition. Such attacks have also been reported in some other diseases affecting the CNS, such as systemic lupus erythematosus. However, to our knowledge, they have not been reported in neuro-Behçet's disease (NBD). A patient with NBD who developed paroxysmal dysarthriaataxia attacks is presented, and the similarity of some clinical, laboratory, and neuroradiological aspects of NBD and MS are discussed with special emphasis on magnetic resonance imaging findings.

Myelin basic protein-specific T lymphocyte repertoire in multiple sclerosis. Complexity of the response and dominance of nested epitopes due to recruitment of multiple T cell clones

The human T cell response to the myelin basic protein (MBP) has been studied with respect to T cell receptor (TCR) usage, HLA class II restriction elements, and epitope specificity using a total of 215 long-term MBP-specific T cell lines (TCL) isolated from the peripheral blood of 13 patients with multiple sclerosis (MS) and 10 healthy donors. In most donors, the anti-MBP response was exceedingly heterogeneous. Using a panel of overlapping synthetic peptides spanning the entire length of human MBP, at least 26 epitopes recognized by human TCL could be distinguished. The MBP domain most commonly recognized was sequence 80-105 (31% of MS TCL, and 24% of control TCL). Sequence 29-48 was recognized more frequently by control-derived TCL (24%) than by TCL from MS patients (5%). The MBP epitopes were recognized in the context of DRB1 *0101, DRB5*0101, DRB1*1501, DRB1*0301, DRB1*0401, DRB1*1402, and DRB3*0102, as demonstrated using a panel of DR gene-transfected L cells. The TCR gene usage was also heterogeneous. V beta 5.2, a peptide of which is currently being used in a clinical trial for treatment of MS patients, was expressed by only one of our TCL. However, within this complex pattern of MBP-specific T cell responses, a minority of MS patients were found to exhibit a more restricted response with respect to their TCL epitope specificity. In these patients 75-87% of the TCL responded to a single, patient-specific cluster of immunodominant T cell epitopes located within a small (20-amino acid) domain of MBP. These nested clusters of immunodominant epitopes were noted within the amino acids 80-105, 108-131, and 131-153. The T cell response to the immunodominant epitopes was not monoclonal, but heterogeneous, with respect to fine specificity, TCR usage, and even HLA restriction. In one patient (H.K.), this restricted epitope profile remained stable for > 2 yr. The TCR beta chain sequences of TCL specific for the immunodominant region of HK are consistent with an oligoclonal response against the epitopes of this region (80-105). Further, two pairs of identical sequences were established from TCL generated from this patient at different times (June 1990 and June 1991), suggesting that some TCL specific for the immunodominant region persisted in the peripheral repertoire. The possible role of persistent immunodominant epitope clusters in the pathogenesis of MS remains to be established.

Human T cell autoimmunity against myelin basic protein: CD4+ cells recognizing epitopes of the T cell receptor beta chain from a myelin basic protein-specific T cell clone

We have investigated whether the normal immune system contains T cells that are able to recognize T cell receptor (TcR) determinants of autologous autoantigen-specific T cells. The T cell clone HW.BP3, specific for myelin basic protein (MBP) was isolated from a healthy donor. HW.BP3 is restricted by HLA-DR2a, and reacts to human MBP 139-153. The expressed alpha beta TcR genes of HW.BP3 were cloned and sequenced, and the sequences analyzed for potential T cell epitopes. Two synthetic peptides, one from the VDJ beta junctional (beta 1) and one from the V beta region (beta 2) of the TcR of HW.BP3, were used to select four TcR peptide-specific T cell lines from the donor of HW.BP3. All anti-TcR lines had the phenotype CD3+/CD4+/HLA-DR+/CD25+/CD45RO+, and recognized the antigen in the context of HLA-DR. Three anti-TcR lines, which had been selected for reactivity to peptide beta 1, recognized exclusively this peptide restricted by HLA-DR2b. One anti-TcR line, selected for peptide beta 2, responded to both peptides beta 1 and beta 2 when presented by autologous blood mononuclear cells, but not by HLA-DR2a- or HLA-DR2b-transfected L cells. All TcR peptide-specific T cell lines were efficiently cytotoxic. They specifically lysed autologous macrophages or HW.BP3 line cells in the presence of exogenous peptide antigen. In contrast, HW.BP3 did not present endogenous TcR peptides to the anti-TcR lines. The results demonstrate that the normal human immune system contains not only autoantigen-specific T cells, but also T cells that recognize antigenic determinants of autologous autoreactive TcR.