Two DR2-associated novel alleles arose from the silent mutation of codon 72: DRB1*16012, DRB5*01012

Two DRB1*02-associated alleles, DRB1*16012 and DRB5*01012, are described. Both alleles carry the same silent substitution at codon 72.

A BCR-ABL oncoprotein p210b2a2 fusion region sequence is recognized by HLA-DR2a restricted cytotoxic T lymphocytes and presented by HLA-DR matched cells transfected with an Ii(b2a2) construct

Peptides corresponding to the fusion site in 210 kD BCR-ABL protein b3a2 (p210b3a2) were previously shown to bind to several HLA class I and II alleles. We have found that b3a2 peptide-specific CD4-positive T-helper cells were able to recognize p210b3a2-positive chronic myelogenous leukemia (CML) blasts in a DR4 restricted manner. Until now, there were no reports of b2a2 breakpoint-specific human T-cell responses. Here we show that repetitive stimulation of T lymphocytes with a 17mer peptide covering the fusion region in p210b2a2 also leads to specific T-cell responses. CD4 and CD4/CD8 double-positive clones obtained from a b2a2 peptide-specific cell line were cytotoxic and proliferative in an HLA-DR2a (DRB5*0101) restricted fashion. Autologous Epstein-Barr virus (EBV) transformed cells, expressing BCR-ABL(b2a2) on transfection, and allogeneic HLA-DR matched p210b2a2-positive cells from CML patients were, however, not lysed. BCR-ABL peptide-specific T-cell clones did respond to autologous EBV cells transfected with invariant chain (li) cDNA in which the HLA class II-associated invariant chain peptide (CLIP) was replaced by a BCR-ABL b2a2 fusion oligonucleotide sequence, illustrating the potential of these T cells to recognize an endogenous BCR-ABL(b2a2) ligand.

Familial Guillain-Barre syndrome

There are few reports of Guillain-Barre Syndrome (GBS) occurring in families. We have encountered a mother, who developed acute inflammatory demyelinating polyradiculoneuropathy at age 35 years, whose son developed the bulbar form of GBS 7 years later. Both shared HLA DR2.

A search for a mutation in the tumour necrosis factor-alpha gene in narcolepsy

The discovery of almost 100% association of narcolepsy with human leukocyte antigens (HLA) DR2 antigen prompted molecular biological research of this disorder. In the HLA class II gene cluster, the gene for tumour necrosis factor-alpha (TNF-alpha), which plays a role in the regulation of normal human sleep, is located. The present study searched for a mutation in the TNF-alpha gene by single-strand conformation polymorphism analysis (SSCP) in patients with narcolepsy. No mutation was detected in exons and introns of the TNF-alpha gene by SSCP and sequencing.

[Study on the association between tumor necrosis factor alpha gene polymorphism and systemic lupus erythematosus]

OBJECTIVE

To examine whether polymorphism within the tumor necrosis factor alpha (TNFalpha) gene is associated with the susceptibility and clinic manifestations to systemic lupus erythematosus (SLE) in the patients of Han ethnic group collected from the Northern China.

METHODS

TNF(1) and TNF(2) subtypes of TNFalpha gene were defined by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis in 89 Chinese patients with SLE and 70 ethnically matched controls from Peking Union Medical College Hospital. All SLE patients were diagnosed by the American Rheumatological Association SLE diagnostic criteria setup in 1982. Human leukocyte antigen (HLA)-DR(2) gene frequency was assigned by PCR with sequence-specific primers (SSP-PCR).

RESULTS

The frequencies of TNF(2) and HLA-DR(2) were significantly increased in SLE patients respectively compared to that of the controls (0.23 vs 0.14, RR = 1.85, P < 0.05; 0.36 vs 0.22, RR = 2.02, P < 0.01). Both TNF(2) and HLA-DR(2) were associated with SLE independently (RR = 3.96, P < 0.05; RR = 3.07, P < 0.05), but there was no association between the two genes. In TNF(2) positive patients, the positive rate of anti-SSA antibody was apparently higher and the incidence of lupus nephritis was significantly increased.

CONCLUSION

Both TNF(2) and HLA-DR(2) gene may play a role in SLE susceptibility. Anti-SSA antibody and lupus nephritis were strongly associated with TNF(2) gene.

Lack of association between HLA-DRB1 alleles of the major histocompatibility complex and p-ANCA status or clinical characteristics in patients with ulcerative colitis

INTRODUCTION

An association between different HLA-subtypes and ulcerative colitis has been described in various study populations of different ethnic and geographic background. Moreover, a correlation between HLA-DR2 and ulcerative colitis, in particular p-ANCA-positive ulcerative colitis, was reported. Thus, the present study aimed on the correlation of HLA-DRB1* alleles with the presence of p-ANCA and clinical characteristics in individuals of southern german descent.

PATIENTS AND METHODS

The study population comprised 56 patients with ulcerative colitis and 177 healthy controls. HLA-DRB1* alleles were assessed by use of the dot blot method. Autoanti-bodies were visualized by indirect immunofluorescence on ethanol-fixed neutrophils.

RESULTS

The allele HLA-DRB1*12 was more frequent in patients with ulcerative colitis (p = 0.01). After correction for the number of alleles tested (n = 16) statistical significance was no longer preserved. A weak association between the presence of HLA-DR5 and the detection of p-ANCA in ulcerative colitis was found (p = 0.0375). After correction for the number of comparisons (n = 10) no associations between HLA-DR antigens and the presence of p-ANCA remained. Furthermore, no significant correlations between clinical characteristics of ulcerative colitis and HLA-DR antigens were detected.

DISCUSSION

Genes encoding for HLA-DR antigens are unlikely to have an impact on the heredity and the presence of disease phenotypes of ulcerative colitis in a study population of southern german descent.

Chromosome 6p-encoded HLA-DR2 determination discriminates migraine without aura from migraine with aura

Segregation analysis indicates that migraine without aura (MWoA) and migraine with aura (MWA) have multifactorial inheritance, but involved genetic and environmental factors are largely unknown. A controlled study was performed to assess the HLA-driven liability to migraine and to verify if the heterogeneity between MWoA and MWA is HLA-linked. Forty-five migraine patients (31 MWoA, 14 MWA) and 53 healthy blood donors as controls, coming from the same geographic area, were studied. Tissue typing was performed using the standard complement-dependent microlymphocytotoxicity technique for HLA Class I and by PCR-SSP (Sequences Specific Primers) typing for HLA Class II. Data emerging from the present study showed no altered distribution for HLA Class I A, B, C antigen frequency in migraine (MWoA, MWA) if compared to the control group. HLA Class II DR2 antigen showed a decreased frequency in MWA group if compared with both MWoA (p = 0.01) and control group (p = 0.039, RR = 0.21). These results seem to support the hypothesis of a protective role of DR2 antigen in MWA and provide additional basis for the proposed difference within MWoA and MWA.

Association of human leucocyte antigen phenotype with vaccine efficacy in patients receiving vaginal mucosal immunization for recurrent urinary tract infection

Immune responses to specific antigens can be influenced by an individual's genetic make-up. We examined whether the efficacy of a vaginal mucosal vaccine for urinary tract infections (UTI) was affected by a patient's human leucocyte antigen (HLA) phenotype. Urinary tract infection data and the HLA phenotypes of 47 women participating in a phase II clinical trial of immunization for recurrent UTI were statistically analysed for associations between HLA-A, -B, -DR, or -DQ phenotype and postimmunization infection course. Women who received the vaccine and had HLA-DR phenotypes other than DR2 had significantly delayed times to re-infection compared with women receiving placebo. Vaccine-treated patients with the HLA-DR2 phenotype had re-infection courses that were not different than women receiving placebo. These results indicate that the efficacy of a vaginal mucosal UTI vaccine may be influenced by an individual's HLA-DR phenotype.

Immunogenetic analysis of Buerger's disease in India

In order to understand the role of HLA linked factors in determining susceptibility to Buerger's disease, we have studied 21 unrelated Asian Indian patients belonging to the North Indian states of Punjab, Haryana, Uttar Pradesh and Delhi, representing mainly a lower socioeconomic background. The data was compared with healthy controls belonging to the same ethnic group. The study revealed an over representation of HLA-B40 (60+61) (chi2=6.12; P<0.02) and DR2 (chi2=10.2; P<0.002). Amongst the patients no particular association or linkage disequilibrium with any of the five alleles of the MIC-A gene could be derived in the small sample size studied.

Cervical carcinoma: human papillomavirus infection and HLA-associated risk factors in the Spanish population

There is evidence for a link between MHC and squamous cell carcinoma of the cervix (SCCC), and different patterns of association in different patient cohorts have been reported. To investigate this subject in the Spanish population, HLA class I, -II serotypings and HLA-DQB1 oligogenotypings of 142 patients and 138 healthy sex-age-matched controls were performed. Comparative analysis of the DR2-DQ3-stratified phenotypes demonstrated a strong association between DR2 and DQ3 in SCCC (Pc9 < 7 x 10(-8)). However, no interaction was observed between the two HLA factors, which seem to confer two weak and independent risks. Thus, phenotypes with DR2 and/or DQ3 (patients, 79%, controls, 60%; P < 5 x 10(-4)) were over-represented, while the less common DR2/DQ3-negative phenotypes with the HLA class I A2 antigen were found to confer the highest risk (EF = 62%, Pc84 < 1 x 10(-2)) of SCCC. Comparative analysis of allele frequencies revealed two weakly significant increases, one for DQB1*0301 (P < 1 x 10(-2)) in low-moderate dysplasias (CINI,II), and the other for DQB1*0402 (P < 3 x 10(-2)) in severe dysplasia in situ (CINIII/CIS), and a trend for an increase of DQB1*0302 among CINIII/CIS and invasive SCCC (ISCCC). With regard to DQB1 genes encoding the DR2-associated DQ serotypes, there was no significant deviation in patients. In contrast, the frequency of DQB1*0603 was found to be weakly decreased in CINI,II (P < 5 x 10(-2)) and ISCCC (P < 3 x 10(-2)), indicating a protective effect for this DR13 serotype-associated allele. No significant association could be shown between HLA and HPV infective status. However, there is circumstantial evidence that HPV-infected lesions may have been misassigned in some cases, and the sample size was small, so a role for DQB alleles in modifying the course of HPV-induced diseases cannot be excluded. The observations in this study suggest A2, DR2, DQB1*0301, DQB1*0402 and DQB1*0603 as independent factors associated with SCCC and as relevant targets in HLA-restricted peptide presentation. Our results are consistent with the theory that HLA loci may have different contributions in susceptibility and resistance to low-moderate dysplasias, CIS and invasive SCCC.

Expression and crystallization of the complex of HLA-DR2 (DRA, DRB1*1501) and an immunodominant peptide of human myelin basic protein

HLA-DR2 is associated with susceptibility to multiple sclerosis (MS). A peptide from human myelin basic protein (MBP, residues 85-99) was previously found to bind to purified HLA-DR2 (DRA, DRB1*1501) and to be recognized by human MBP-specific T cell clones. Soluble HLA-DR2 was expressed in the baculovirus system by replacing the hydrophobic transmembrane regions and cytoplasmic segments of DRalpha and DRbeta with leucine zipper dimerization domains from the transcription factors Fos and Jun. In the expression construct, the MBP(85-99) sequence was covalently linked to the N terminus of the mature DRbeta chain. The recombinant protein was secreted by Sf9 cells infected with the recombinant baculovirus and purified by affinity chromatography. The leucine zipper dimerization domains were then cleaved from the assembled HLA-DR2/MBP peptide complex with V8 protease, and the protein was further purified by anion-exchange HPLC. Analysis by HPLC gel filtration indicated that the HLA-DR2/MBP peptide complex did not have a tendency to aggregate. The purified HLA-DR2/MBP peptide complex readily crystallized by the hanging drop method in 15-18% polyethylene glycol 6000/100 mM glycine, pH 3.5. At a synchrotron radiation source, a crystal with a tetragonal space group diffracted to a resolution of 2.6 A. The expression of such homogenous HLA-DR/peptide complexes may facilitate cocrystallization with T cell receptors as well as other molecules involved in T cell receptor recognition and signaling.

Polymorphism and distribution of HLA-DR2 alleles and haplotypes in a Greek population

HLA-DR2 serological subtyping has indicated that the DR16 serotype appears at a higher frequency relative to the DR15 serotype in the Greek population, differing from the distribution observed in most other Caucasian groups. In this study, we have analyzed by the PCR-SSP technique a DR2-positive group of unrelated Greek individuals selected from our normal control panel for the different DRB1, DRB5, DQB1 and DQA1 DR2-associated alleles present. Six of the 50 individuals analyzed were homozygous for DR2, contributing a total of 56 haplotypes for DR2. The observed frequencies of the DR2-related DRB1 alleles were as follows: 58.9% for the DRB1*1601, 7.1% for the DRB1*1602, 25.0% for the DRB1*1501 and 7.1 % for the DRB1*1502 allele. The rare allele DRB1*1605 was detected in one heterozygous sample and its presence was definitively established by DNA sequencing. The alleles *1503, *1504, *1505, *1603 and *1604 were not detected. Three DRB5 alleles were identified: DRB5*0202 (67.8%), DRB5*0101 (25.0%) and DRB5*0102 (7.1%). Ten different DRB1/DQB1/ DQA1 DR2-associated haplotypes were defined. The most frequently observed haplotype was DRB1*1601-DQB1*0502-DQA1*0102 (relative frequency=57%) followed by DRB1*1501-DQB1*0602-DQA1*0102 (relative frequency=14.3%). In conclusion, the refined analysis of the DR2-associated DRB1 alleles in the Greek population revealed the prevalence of the DRB1*1601 allele. The rare allele DRB1*1605 was demonstrated once. A considerable variety of different DR2-related DR/DQ haplotypes was detected and the overall haplotypic frequencies in the Greek population are distributed differently compared to those reported for most other Caucasian populations.

Diversity of HLA-DR2 in North Indians: the changed scenario after the discovery of DRB1*1506

DRB1*1506, a new allele of DR2, differs from DRB1*1501 only at codon 50 in the second exon, where the nucleotide sequence has changed from GTG to GCG resulting in an amino acid substitution from valine to alanine in DRB1*1506. Since codon 50 was considered non-polymorphic until the discovery of this new allele by sequence-based typing, it became necessary to study what fraction of subjects thought to have DRB1*1501 actually had DRB1*1506. For this purpose, 116 DNA samples with DR2 coming from normal healthy individuals, leprosy patients and childhood tuberculosis patients were amplified using PCR and hybridized with 32P-labeled probes specific for DRB1*1501, DRB1*1502, DRB1*1503, DRB1*1506, DRB1*1601 and DRB1*1602. The oligonucleotide probe for DRB1*1506 was designed to span codons 47-52 based on the published nucleotide sequence. DRB5, DQA1 and DQB1-specific amplifications and hybridizations were also carried out to study the diversity of DR2 haplotypes. It was found that 21% of the samples identified previously as DRB1*1501 were actually DRB1*1506. DRB1*1506 was found to be associated with DQB1*0502 and DQB1*0601. Haplotypes of DRB1*1501, DRB1*1502, DRB1*1506 and DRB1*1602 showed a marked heterogeneity. Besides the rare haplotypes which have not yet been reported in any other populations, haplotypes characteristic of different ethnic groups, such as Croatians, South Chinese and Gypsies, were also found in the North Indians, suggesting the extent of racial admixture and migrations to and from India.

Immunity to T cell receptor peptides in multiple sclerosis. III. Preferential immunogenicity of complementarity-determining region 2 peptides from disease-associated T cell receptor BV genes

Vaccination with synthetic TCR peptides from the BV5S2 complementarity-determining region 2 (CDR2) can boost significantly the frequency of circulating CD4+ peptide-specific Th2 cells in multiple sclerosis (MS) patients, with an associated decrease in the frequency of myelin basic protein (MBP)-reactive Th1 cells and possible clinical benefit. To evaluate the immunogenicity of CDR2 vs other regions of the TCR, we vaccinated seven MS patients with overlapping BV5S2 peptides spanning amino acids 1-94. Six patients responded to at least one of three overlapping or substituted CDR2 peptides possessing a core epitope of residues 44-52, and one patient also responded to a CDR1 peptide. Of the CDR2 peptides, the substituted (Y49T)BV5S2-38-58 peptide was the most immunogenic but cross-reacted with the native sequence and had the strongest binding affinity for MS-associated HLA-DR2 alleles, suggesting that position 49 is an MHC rather than a TCR contact residue. Two MS patients who did not respond to BV5S2 peptides were immunized successfully with CDR2 peptides from different BV gene families overexpressed by their MBP-specific T cells. Taken together, these results suggest that a widely active vaccine for MS might well involve a limited set of slightly modified CDR2 peptides from BV genes involved in T cell recognition of MBP.

Influence of HLA-DR2 phenotype on humoral immunity & lymphocyte response to Mycobacterium tuberculosis culture filtrate antigens in pulmonary tuberculosis

Association of HLA-DR2 genes/gene products has been shown with pulmonary tuberculosis (PTB) patients in India. In the present study, the influence of HLA-DR2 and non-DR2 genes/gene products on immunity to tuberculosis has been studied. Plasma samples of -DR2 positive patients (active and inactive TB) showed a higher antibody titre to Mycobacterium tuberculosis culture filtrate antigens than non-DR2 (-DR2 negative) patients. Immunoblot analysis revealed a trend towards an increased percentage of DR2 positive patients recognizing 38, 32/34 and 30/31 kDa antigens of M. tuberculosis than DR2 negative patients. A low spontaneous lymphoproliferative response (without antigen stimulation) was seen in HLA-DR2 positive active TB patients than HLA-DR2 negative patients. However, the antigen stimulated lymphocyte response was higher in the -DR2 positive patients (active and inactive TB) when compared to non-DR2 patients. Further, an inversional correlation between antibody titre and spontaneous as well as antigen induced lymphocyte response (measured by 3H thymidine uptake and expressed as counts per minute) was seen in HLA-DR2 positive active PTB patients than non-DR2 patients. The present study suggests that HLA-DR2 genes/gene products may be associated with a regulatory role in the mechanism of disease susceptibility to tuberculosis. The genes while augmenting the humoral immune response, they suppress the spontaneous and antigen induced lymphocyte response in -DR2 positive patients with active disease.

Multiple sclerosis: the frequency of allelic forms of tumor necrosis factor and lymphotoxin-alpha

The cytokines LTa and TNF have been implicated as major mediators of tissue injury in multiple sclerosis (MS). In this study we have assessed the frequency of specific polymorphisms for these genes in MS (n = 53) and controls (n = 81) using a highly sensitive, two stage nested polymerase chain reaction (PCR), with the second stage using mutation-specific primers. Genomic DNA was extracted from blood cells and the results confirmed by direct dideoxy chain termination sequencing. The frequency of the -308 G to A mutation in the TNF promoter region in normal controls was 15% and in MS was 24%. For LTa gene the exon 3 polymorphism allele A was detected in 36% of controls and 34% of the MS patients. In MS, the combined genotype TNF G + A and LTa C + C was present 6 times more frequently (12%) than in controls (2%), and patients with this genotype showed the highest EDSS scores. We found the TNF and LTa polymorphisms to occur independently from the HLA class II DR2 allele distribution in MS. Whilst the G - A polymorphism in TNF gene promoter has been studied previously in MS, with conflicting results, this is the first study that has addressed the exon 3 polymorphism in LTa in MS. The results indicate that this polymorphism is not linked with the higher genetic predisposition for MS, but that combined TNF G + A and LTa C + C genotype might contribute to development of the disease.

Familial evidence of vasospastic angina and possible involvement of HLA-DR2 in susceptibility to coronary spasm

An association between genetic factors and susceptibility to coronary spasm has not been proven. Because we encountered 7 patients with familial occurrence of vasospastic angina (VSA) in 3 families, the association of a genetic factor with coronary spasm was assumed. HLA typing as one of the genetic markers was performed in the 3 families, and the affected members in each family were found to share a HLA haplotype, carrying both HLA-DR52 and DQ6. This raised the possibility that one of the susceptibility genes for coronary spasm is located in the HLA region. To assess this possibility, HLA typing was performed and compared in 110 patients with VSA but without a family history of VSA (VSA group) and 55 patients with chest pain syndrome (CPS group) as control subjects. All patients underwent a provocation test for coronary spasm, and spasm was angiographically documented in the VSA group but not in the CPS group. Of all HLA antigens, the frequency of only HLA-DR2 was significantly higher in the VSA group than in the CPS group (39.1% vs 18.2%, p<0.01). The result implied that HLA-DR2 is in linkage disequilibrium with a susceptibility gene of VSA and thus is possibly involved in susceptibility to coronary spasm in some patients with VSA.

HLA-DR2 gene and Spanish patients with ulcerative colitis

BACKGROUND

An association with class II MHC genes has been described in ulcerative colitis, as in other diseases with immunological pathogenesis. Heterogeneous results have been reported, depending on the studied population.

OBJECTIVE

To study the importance of these genes in our population, mainly the alleles of group HLA DR2 (gene HLA-DRB1).

PATIENTS AND METHODS

We studied a total of 107 patients diagnosed of ulcerative colitis and 200 unaffected controls. Complete information about sex, age, family antecedent, age of onset, localization, complications, surgery and treatment was obtained from these patients. DNA was extracted from peripheral blood leukocytes and all the individuals were HLA-DRB1 genotyping.

RESULTS AND CONCLUSIONS

We conclude that a positive association exists between DR15 and ulcerative colitis (p < 0.05). This positive association was characterized and various clinical parameters were analyzed, being concluded that DR1501 is more frequent in this disease (p < 0.05) and in benign manifestations; the frequency of the allele DR1502 was also found to be elevated in severe manifestations.

HLA antigen profile in pulmonary tuberculosis patients & their spouses

HLA-A, -B, -DR and -DQ antigen profile was studied in pulmonary tuberculosis patients (n = 209) and their spouses (family contacts; n = 50) and healthy volunteers (n = 72). An increased frequency of HLA-A-10, B7, B15, DR2 and DQ1 was seen in the pulmonary-TB (PTB) patients when compared to the total control subjects (n = 122). However, a significant increase was seen only with HLA-DR2 (P < 0.001; Pc < 0.01; Relative Risk 2.3) and -DQ1 (P < 0.005; Pc < 0.015; Relative Risk 2.8). Among the spouses and the corresponding patients, a similar increase of HLA-DR2 was seen. A decreased frequency of HLA-A19, B8, B17, B35, DR5 and DR6 were seen in PTB as compared to control groups. The present study suggested that HLA-DR2 and DQ1 genes/gene products may be associated with the susceptibility to tuberculosis either alone or in combination with other HLA or non-HLA genes.

Genetic risk factor for abdominal aortic aneurysm: HLA-DR2(15), a Japanese study

PURPOSE

Autoimmunity has been proposed to play a role in the pathogenesis of the abdominal aortic aneurysm (AAA). Several autoimmune diseases are associated with specific HLA DR alleles. These experiments were carried out to determine whether the same HLA DR types that have been reported to be associated with AAA in a mixed North American population are similarly associated with AAA in a more homogeneous group of patients in Japan.

METHOD

HLA DR typing was performed by a serologic method on samples of peripheral blood of patients with nonspecific infrarenal AAA in Nagasaki University Hospital in Japan. The frequencies of HLA DR antigens were compared with those of volunteers approximately matched for age and sex from the same referral area.

RESULTS

HLA DR haplotypes were determined in 46 Japanese patients with AAA and in 50 patients in a control group. The HLA-DR2(15) antigen was observed in 27 (58.7%) patients (29 alleles 31.5%) with AAA and in 14 (28%) subjects (16 alleles 26.0%) in the control group (p < 0.005).

CONCLUSIONS

The data suggest that HLA-DR2(15) has an important role as a genetic risk factor for AAA in Japanese patients, as previously reported in a mixed North American population.

HLA class II phenotype controls diversification of the autoantibody response in primary Sjögren's syndrome (pSS)

The coexistence of anti-La (SS-B) and anti-Ro (SS-A) autoantibodies in pSS is probably explained by intermolecular spreading of autoimmunity toward different components of the La/Ro ribonucleoprotein (RNP). In order to evaluate the role of the HLA class II phenotype in controlling diversification of this autoantibody response, 80 patients with pSS were typed by polymerase chain reaction sequence-specific oligonucleotide (PCR-SSO) at the HLA class II loci DRB1, DQA1 and DQB1. Serum samples were examined for anti-La and anti-Ro by counterimmunoelectrophoresis and by ELISA using purified recombinant La and 60-kD Ro proteins. Patient sera were classified according to the extent of diversification of the anti-La, anti-Ro response including the presence or absence of precipitating anti-La antibodies. Immunogenic characteristics of these stratified groups were then studied. All patients with pSS, with or without autoantibodies to Ro and La, were found to have at least one of the HLA-DRB1 types DR2, DR3 or DR5. The HLA DR3-DQA1*0501-DQB1*02 (DR3-DQ2) haplotype was primarily associated with a diversified La/Ro RNP response containing precipitating autoantibodies to La (P<0.001); whereas the haplotype HLA DR2-DQA1*0102-DQB1*0602 (DR2-DQ1) was associated with a less diversified La/Ro RNP response containing non-precipitating (restricted epitope) anti-La autoantibodies (P<0.001). Anti-La-positive patients lacking both HLA-DR2 and HLA-DR3 all expressed the HLA-DQA1*0501 allele, which was present at increasing frequency with greater diversification of the anti-La/Ro autoantibody response. The association of distinct HLA haplotypes with different degrees of autoantibody diversification in patients with pSS suggests a model of HLA-restricted presentation of La/Ro peptide determinants to autoreactive helper T cells. We propose that non-precipitating anti-La responses are driven by limited intermolecular help from DR2-DQ1-restricted T helper cells recognizing Ro determinants. On the other hand, we speculate that the more diversified, precipitating anti-La responses obtain more efficient cognate T help from DR3-DQ2-restricted T helper cells recognizing La determinants, where HLA-DQA1*0501 may be a critical determinant for antigen presentation.

CD95 expression and CD95-mediated apoptosis of T cells in multiple sclerosis. No differences from normal individuals and no relation to HLA-DR2

CD95-mediated apoptosis is a potent endogenous pathway of T cell elimination that has been suggested to be altered in multiple sclerosis (MS). MS is associated with the HLA-DR2, Dw2, DQ6 HLA class II haplotype. We have previously reported that T cell lines from HLA-DR2-positive individuals show enhanced production of tumor necrosis factor (TNF), a cytokine homologous to CD95 ligand, in response to specific antigen. Here we have studied CD95 expression and susceptibility to CD95-mediated apoptosis in peripheral blood mononuclear cells (PBMC) and activated T cells of 20 healthy individuals and 20 MS patients, half of whom were HLA-DR2-positive. MS patients did not differ from healthy individuals in either parameter. There was also no difference in CD95 expression or CD95-mediated apoptosis when MS patients and healthy individuals were grouped and compared according to HLA-DR status. These data reveal no differential regulation of PBMC/T cell apoptosis induced by CD95 receptor ligation in MS and show no impact of HLA-DR2 status on PBMC/T cell susceptibility to the same apoptotic stimulus. However, to assess the contribution of T cell apoptosis to the pathogenesis of MS further studies on other details of the complex system leading to T cell apoptosis are required.

Testing candidate genes that may affect susceptibility to leprosy

Several statistical methods have been used to search familial data sets for marker alleles associated with the occurrence of a disease. In the present paper, a recently developed method is used to re-analyze published data on leprosy and candidate genes at the HLA loci. This new method of analysis, the randomization transmission disequilibrium test (TDT), confirmed previous conclusions that there was no significant evidence against random transmission at the HLA-A locus but significant positive association with the HLA-DR2 allele. The randomization TDT detected significant protective associations, that had not previously been found, with alleles HLA-B8 in Egyptian families and HLA-B21 (current nomenclature B x 4901, 5001-5002) in South Indian families, highlighting a major advantage of permutation tests in analyzing candidate gene loci with rare alleles. These findings provide evidence that HLA class I restricted T lymphocytes may be of protective importance in leprosy.

The absence of DR51 in a DRB5-positive individual DR2ES is caused by a null allele (DRB5*0108N)

DR51, a protein encoded by the DRB5 gene, was shown to be present in almost all DR2-positive haplotypes. Exceptions were reported, some DR2-negative samples were shown to be DR51 positive and in a number of DR2-positive samples no DR51 antigen could be demonstrated. In some of them lack of the DRB5 gene was the cause of the absence of DR51 but in others the DRB5 gene was present without resulting in a detectable gene product. Many of these variants were studied in detail in previous international workshops. One of them was DR2ES from our laboratory. She is a DR15-positive DR51-negative individual of oriental origin with a clearly demonstrable DRB5*01 allele when typed by molecular techniques. To unravel the molecular mechanism responsible for the defect in expression, cDNA and DNA encoding the defective DRB5 allele were analyzed. Nucleotide sequence analysis of exon 2 showed no differences from the sequence of DRB5*0102. However, when exon 3 was examined a difference in length was noticed due to a deletion of 19 nucleotides between codon 161 and 168. The deletion caused a frameshift and a premature stopcodon resulting in a null allele. The same allele could be demonstrated in 6 other unrelated individuals of oriental origin as well as in 5 individuals from South Africa. The absence of the DR51 protein was explained by the presence of an alteration in the DRB5 allele resulting in a null allele. The allele has been officially named DRB5*0108N. This is the first description of a null allele of the DRB5 gene.