HLA-DR typing in polyarticular juvenile idiopathic arthritis: a study from a tertiary care hospital in northern India.

INTRODUCTION: Many studies of human leukocyte antigen (HLA) association with juvenile idiopathic arthritis (JIA) have reported conflicting results, which were probably related to ethnic differences. Moreover, in India, studies on HLA-DR typing on JIA, particularly polyarticular JIA, is lacking. OBJECTIVE: The aim of our study was to reveal the frequency of HLA DR types in a cohort of polyarticular JIA in northern India. METHODS: Fifty-two polyarticular JIA patients were included as per the recent International League of Associations for Rheumatology classification, 2001. HLA-DR typing was performed in 21 patients (18 rheumatoid factor [RF]+ and three RF-) by a DNA-based polymerase chain reaction method for the determination of HLA alleles using sequence specific primers (SSP). The results were compared with that of 23 healthy controls of the same age and sex. RESULTS: HLA-DR4 was present in five cases (23%) in the diseased group while only in one case (4.3%) in the control group with a relative risk of 5.47, but when compared with only RF+ polyarticular JIA, HLA-DR4 was found to be significantly high (27.7% vs. 4.43%; P < 0.05) with a relative risk of 6.3. Further, DR4, DR1, DR2, DR9, DR10 were also non-significantly high in these patients with relative risk of 3.2 for DR9 and 1.8 for DR10. In contrast, HLA-DR6 was seen only in 5.5% of polyarticular JIA cases, whereas it was present in 39% of controls (P < 0.05), a showing negative association. CONCLUSION: HLA-DR4 codes for susceptibility to RF+ polyarticular JIA with a six-fold risk, whereas HLA-DR6 offers protection.

Human leukocyte antigens and systemic lupus erythematosus: a protective role for the HLA-DR6 alleles DRB1*13:02 and *14:03.

Many studies on associations between human leukocyte antigen (HLA) allele frequencies and susceptibility to systemic lupus erythematosus (SLE) have been performed. However, few protective associations with HLA-DRB1 alleles have been reported. Here, we sought protective, as well as predispositional, alleles of HLA-DRB1 in Japanese SLE patients. An association study was conducted for HLA-DRB1 in Japanese SLE patients. Relative predispositional effects were analyzed by sequential elimination of carriers of each allele with the strongest association. We also explored the association of DRB1 alleles with SLE phenotypes including the presence of autoantibody and clinical manifestations. Significantly different carrier frequencies of certain DRB1 alleles were found to be associated with SLE as follows: increased DRB1*15:01 (P = 5.48×10⁻¹°, corrected P (Pc) = 1.59×10⁻8, odds ratio [OR] 2.17, 95% confidence interval [CI] 1.69-2.79), decreased DRB1*13:02 (P = 7.17×10⁻5, Pc = 0.0020, OR 0.46, 95% CI 0.34-0.63) and decreased DRB1*14:03 (P = 0.0010, Pc = 0.0272, OR 0.34, 95% CI 0.18-0.63). Additionally, the "*15:01/*13:02 or *14:03" genotype tended to be negatively associated with SLE (P = 0.4209, OR 0.66), despite there being significant positive associations with *15:01 when present together with alleles other than *13:02 or *14:03 (P = 1.79×10⁻¹¹, OR 2.39, 95% CI 1.84-3.10). This protective effect of *13:02 and *14:03 was also confirmed in SLE patients with different clinical phenotypes. To the best of our knowledge, this is the first report of a protective association between the carrier frequencies of HLA-DRB1*13:02 and *14:03 and SLE in the Japanese population.

HLA-DR6 association confers increased resistance to T. rubrum onychomycosis in Mexican Mestizos.

BACKGROUND: Onychomycosis is multifactorial in origin. Studies have suggested an autosomal dominant pattern of inheritance and human leukocyte antigen DR4 (HLA-DR4) has been shown to protect against onychomycosis in an Ashkenazi Jewish population. AIM: This study investigates HLA class II association in a Mexican Mestizo population with Trichophyton rubrum onychomycosis. METHODS: This was a prospective case-control study. Mexican Mestizos with a clinical diagnosis of onychomycosis and culture positive for T. rubrum were recruited, together with age- and sex-matched controls. First-degree relatives were also investigated for onychomycosis. Case-control samples were HLA typed by polymerase chain reaction sequence-specific primer based analysis. RESULTS: Twenty-one cases and 42 controls were recruited with a mean age of 40 years (range: 18-58 years). HLA-DR6 was found in seven (33%) cases and 19 (45%) controls [P < 0.023, odds ratio (OR) = 0.088, 95% confidence interval (CI): 0.01-0.71]. Six (29%) cases and three (7%) controls had an affected child (P < 0.043, OR = 9.15, 95% CI: 1.07-78.31), and 13 (62%) cases and 12 (29%) controls had an affected first-degree relative (P < 0.02, OR = 4.0, 95% CI: 1.1-14.3). CONCLUSIONS: These results suggest that HLA-DR6 confers protection against the development of onychomycosis in a Mexican Mestizo population. Having an affected first-degree relative significantly increases the risk of onychomycosis, suggesting genetic susceptibility.

Prognostic factors for survival in scleroderma associated pulmonary arterial hypertension.

OBJECTIVE: Identification of prognostic factors for survival in systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH) is necessary for appropriate monitoring, interventions, and timely referral for lung transplantation. Our objectives were (1) to identify factors associated with survival in SSc-PAH and (2) to evaluate the methodologic quality of prognostic studies against current standards. METHODS: A systematic review was performed to identify studies evaluating factors associated with survival in SSc-PAH. The methodologic quality of each study was evaluated using a methodologic quality index. RESULTS: HLA-DRw6 (RR 54.52, p = 0.01), HLA-DRw52 (RR not reported, p = 0.02), initial systolic pulmonary artery pressure (sPAP) > 60 mmHg (HR 3.60, 95% CI 1.42, 9.15), elevated mean right atrial pressure (mRAP) (HR 20.7, p = 0.0001), and shorter time between SSc onset and observed PAH (5.24 vs 9.93 yrs, p < 0.01) were associated with decreased survival. Age > 50 years (HR 2.34, 95% CI 0.54, 10.2), male sex (HR 2.02, 95% CI 0.65, 6.20), limited subtype (HR 2.37, 95% CI 0.68, 8.20), pulmonary fibrosis [Kaplan-Meier (KM) curves, p = 0.3], change in pulmonary vascular resistance (KM curves, p = 0.8), anti-centromere (HR 1.67, 95% CI 0.66, 4.26) and anti-ScL-70 (HR 0.28, 95% CI 0.03, 1.99) antibodies were not definitively associated with survival. Attributes of participants, prognostic factors, and outcome measures were well reported. Study attrition, confounding, and analysis were not well reported. CONCLUSION: HLA-DRw52 and -DRw6, initial sPAP > 60 mmHg, mRAP, and shorter time between SSc onset and observed PAH were associated with decreased survival; however, methodologic quality of study reporting was variable. Prognostic factor research is needed using current methodologic standards.

Particular genetic variants of ligands for natural killer cell receptors may contribute to the HLA associated risk of primary sclerosing cholangitis.

BACKGROUND/AIMS: Combinations of killer immunoglobulin-like receptors (KIRs) and HLA class I ligands that reduce natural killer (NK) cell inhibition have been shown to increase risk for autoimmune diseases. We aimed to clarify to what extent such combinations influence susceptibility to primary sclerosing cholangitis (PSC). METHODS: Three hundred and sixty-five Scandinavian PSC patients and 368 healthy controls were genotyped for the presence or absence of genes encoding all KIRs using a PCR-SSP approach. KIR binding site variation of HLA-A, -B and -C was also determined. RESULTS: The KIR gene frequencies were similar among patients and controls. However, the frequency of HLA-Bw4 and -C2, which are ligands for the inhibitory KIRs 3DL1 and 2DL1, respectively, was significantly reduced in PSC patients as compared with controls (38.2% vs. 54.7%, P(corrected)[P(c)]=0.0006 and 42.7% vs. 56.9%, P(c)=0.009, respectively). Two HLA risk haplotypes in PSC (carrying DRB1*0301 or DRB1*1501, respectively) were devoid of both of these alleles, and carried the 5.1 variant of the major histocompatibility complex class I chain-related A (MICA) gene previously reported to influence PSC susceptibility. CONCLUSIONS: Particular variants of ligands for NK cell receptors encoded at three neighbouring genes in the HLA complex may contribute to PSC associations observed in this genetic region.

Primary sclerosing cholangitis is associated with extended HLA-DR3 and HLA-DR6 haplotypes.

Primary sclerosing cholangitis (PSC) is associated with the human leukocyte antigen (HLA)-DRB1*0301-DQA1*0501-DQB1*0201 (DR3) and HLA-DRB1*1301-DQA1*0103-DQB1*0603 (DR6) haplotypes. Recently, the extended HLA class I region has been found to harbour genes that modulate or confer susceptibility independently of the HLA class II genes in several immune-mediated diseases. The aim of the present study was to evaluate the influence of genes in the extended HLA class I region on susceptibility to PSC. Seven microsatellite markers (MIB, D6S265, D6S2222, D6S464, D6S2223, D6S2225 and D6S2239) were analysed together with HLA class II alleles in 219 Norwegian patients with PSC and 282 random controls. To control for associations because of linkage disequilibrium (LD), 142 HLA-DR3 homozygous and 187 DR6-positive controls were included. The unstratified analysis showed significant associations with the alleles MIB*349 [odds ratio (OR) = 3.0, corrected P value (P(c)) = 3 x 10(-12)], D6S265*122 (OR = 1.7, P(c)= 0.004), D6S464*209 (OR = 1.8, P(c)= 0.03) and D6S2225*147 (OR = 2.7, P(c)= 4 x 10(-6)), which were mainly secondary to the DR3 association. When stratifying for DR6, an association with the D6S265*122 allele was still observed (OR = 3.7, P(c)= 0.0004). In the presence of the D6S265*122 allele, the risk to develop PSC conferred by DR6 was increased four times compared with the risk conferred by DR6 alone. In addition, a novel negative association of PSC with DR11 was observed (OR = 0.21, P(c)= 2 x 10(-4)). In conclusion, our study shows that a gene in LD with D6S265 contributes to susceptibility to develop PSC in individuals carrying DR6. Moreover, we found that the PSC-associated DR3 haplotype extends more telomeric than that previously reported. We also report a possible protective effect of DR11 on development of PSC.

Hepatitis C virus-associated oral lichen planus: is the geographical heterogeneity related to HLA-DR6?

BACKGROUND: The association between hepatitis C virus (HCV) and oral lichen planus (OLP) is more common in the Mediterranean area and Japan, possibly because of immunogenetic factors. METHODS: Intermediate-resolution HLA-DRB typing by hybridization with oligonucleotide probes was performed in 31 Italian OLP patients with HCV infection, in 45 Italian OLP and in 48 British OLP patients without HCV infection. As healthy controls we included data from 145 unrelated Italian and 101 unrelated British bone marrow donors. RESULTS: Italian HCV+ve OLP patients possessed the HLA-DR6 allele more frequently than Italian and British OLP patients without HCV infection (51.6% vs. 17.7% vs. 16.7%; P corrected = 0.028 and 0.017, respectively). There was no difference in the frequency of the HLA-DR6 allele between Italian and British control subjects. CONCLUSIONS: The present data suggest that HLA-DR6 may be responsible for the peculiar geographic heterogeneity of the association between HCV and OLP.

[Relationship between human leukocyte antigen-DRB1 allele gene polymorphism and intrahepatic cholestasis of pregnancy].

OBJECTIVE: To study the relationship between human leukocyte antigen-DRB1 (HLA-DRB1) allele genes polymorphism and intrahepatic cholestasis of pregnancy (ICP). METHODS: Forty-two patients with ICP were tested for HLA-DRB1 allele genes polymorphism with the polymerase chain reaction technique and sequence specific oligonucleotide (PCR-SSO) probes hybridization, 56 normal pregnant women as control group were also tested. In addition, the phenotype frequencies of HLA-DRB1 alleles were compared with it's clinical character in patients with ICP. RESULTS: The higher frequencies were observed for alleles DR9, DR12 and DR4 in both groups. DR6 alleles were detected in 14 cases out of 42 patients. Patients with ICP had a significantly higher frequency of the allele DR6 when compared to control group (16.7% vs 3.6%), with a relative risk (RR) as 6.5 (P < 0.01). No significant differences were observed between the frequencies of other detected HLA-DRB1 alleles in both groups. There was no association between HLA-DR6 allele and the level of liver function and cholylglycine in ICP. CONCLUSION: The study showed that HLA-DR6 gene might be one of the susceptibility genes to ICP.

Cytokine gene polymorphisms and acute human liver graft rejection.

Interindividual differences exist in the capacity to produce cytokines. It has been reported that levels of in vitro cytokine production measured after stimulated cell culture are associated with polymorphisms in cytokine genes. Moreover, a correlation between heart, kidney, liver, and lung graft rejection or survival with cytokine gene polymorphisms has been described. In the present study, we analyzed the association of gene polymorphisms in T helper subtype 1 (T(H)1-), T(H)2-, and regulatory-type cytokines with human liver allograft rejection. Patients who received a primary liver graft from 1992 onward and were seen at the transplant outpatient clinic since then were included on this study (n = 89). Patients were HLA typed routinely. Biopsy-proven acute rejection occurred in 41 of 89 patients. After informed consent, blood was collected and DNA was obtained. Using amplification-refractory mutation system polymerase chain reaction, the following cytokine gene polymorphisms were determined: IL-2+166, IL-2-330, IL-15+13689, IL-15-80, TNF-A-308, TNFd3, IFN-G+874 (T(H)1-type cytokines), IL-4+33, IL-4-590, IL-6-174, IL-10-592, IL-10-819, IL-10-1082, IL-13+2043, IL-13-1055 (T(H)2 type cytokines), TGF-B1+869, and TGF-B1+915 (regulatory-type cytokines). Univariate analysis showed that polymorphisms of IL-10-1082, TGF-B1+869, and HLA-DR6 were significantly related to liver graft rejection. Multiple logistic regression analysis was used to assess which variables remained significantly predictive of acute rejection. Multivariate analysis showed that TGF-B1+869 and HLA-DR6 were independently associated with the occurrence of acute rejection. These findings suggest a role for the regulatory-type cytokine transforming growth factor-beta1 in human liver graft rejection.

Polymorphism of human HLA-DRB1 antigens generated by genetic exchange between DR2 (DRB1*15011) and DR6 (DRB1*1405) alleles: a novel DRB1 allele (DRB1*1437) identified in a Paiwan tribe member of Taiwan.

We report herein the identification of a new DRB1 allele using sequence-based typing (SBT). This novel allele, HLA-DRB1*1437, was found in an aboriginal individual from the Paiwan tribe in the southern part of Taiwan. This individual was typed by SBT method as having an HLA genotype of HLA-A*02011/0203, HLA-B*15011/3901, HLA-DRB1*11011/1437, HLA-DRB3*0202/0202, and HLA-DPB1*0501/1301. This new allele differs from DRB1*1309 in the 5'-end nucleotide sequence of polymorphic exon 2 at codon 16 (CAT-->CAA; H16Q), codon 37 (AAC-->TTC; R37F), codon 47 (TTC-->TAC; F47Y), and codon 58 (GCC-->GCT; both specify alanine). By sequence comparison, it was found that this new allele has a 5'-end sequence (from amino acid residues 7 to 66) identical to that found in the DRB1*1405 allele and a 3'-end sequence (from amino acid residues 58 to 94) identical to that found in the DRB1*15011 allele. Both DRB1*1405 and DRB1*15011 alleles have been identified among the Paiwan members (Note).

Increased frequency of HLA-DR6 allele in Italian patients with hepatitis C virus-associated oral lichen planus.

BACKGROUND: Recent controlled studies have confirmed that hepatitis C virus (HCV) is the main correlate of liver disease in patients with lichen planus (LP), mainly in southern Europe and Japan. However, a low prevalence of HCV infection has been found in LP patients in England and northern France, and significant differences in serum HCV RNA levels or HCV genotypes have not been found between LP patients and controls. Thus host rather than viral factors may be prevalent in the pathogenesis of HCV-related LP. The HLA-DR allele may influence both the outcome of HCV infection and the appearance of symptoms outside the liver. OBJECTIVES: To assess whether major histocompatibility complex class II alleles play a part in the development of HCV-related LP. METHODS: Intermediate-resolution DRB typing by hybridization with oligonucleotide probes was performed in 44 consecutive Italian oral LP (OLP) patients with HCV infection (anti-HCV and HCV RNA positive), in an age, sex and clinically comparable disease control group of 60 Italian OLP patients without HCV infection (anti-HCV and HCV RNA negative), and in 145 healthy unrelated Italian bone marrow donors without evidence of liver disease or history of LP and with negative tests for HCV. RESULTS: Patients with exclusive OLP and HCV infection possessed the HLA-DR6 allele more frequently than patients with exclusive OLP but without HCV infection (52% vs. 18%, respectively; Pc (Pcorrected) = 0.028, relative risk = 4.93). We did not find any relationship between mucocutaneous LP, HCV infection and HLA-DR alleles. CONCLUSIONS: HCV-related OLP therefore appears to be a distinctive subset particularly associated with the HLA class II allele HLA-DR6. This could partially explain the peculiar geographical heterogeneity of the association between HCV and LP.

Age-specific effects of juvenile rheumatoid arthritis-associated HLA alleles.

OBJECTIVE: To define the onset and duration of effect of the HLA alleles that are associated with disease susceptibility and protection in juvenile rheumatoid arthritis (JRA) and 2 of its subtypes. METHODS: We typed 680 patients with JRA and 254 ethnically matched unrelated controls for HLA class I and II genes. The frequency of each allele was calculated for each of the age-at-onset, onset type, and sex categories and plotted against the allele frequency in the control population. Survival analysis (with onset of disease as the terminating event) was used to calculate the age by which 50% (St0.5) and 80% (St0.2) of the children with particular alleles and combinations of alleles develop disease. This allele-specific survival analysis also allowed for the comparison of the overall survival functions for the various JRA subtype and sex categories. RESULTS: Certain alleles are strongly associated with early susceptibility to pauciarticular JRA, including HLA-A2, DR8, DR5, and DPB1*0201. Fifty percent of the children carrying at least 1 of these alleles had disease onset prior to their third birthday. Among children who carried HLA-A2 and any 2 HLA-DR alleles (DR3, DR5, DR6, or DR8), the median age at the onset of pauciarticular disease was 2.7 years. Combinations of A2 and DPB1*0201 and one DR allele narrowed the window further to a median age at onset of 2.4 years. B27 and DR4 were associated with protection early in life but with increased risk later in childhood, with St0.5 values of 7.3 and 6.6 years, respectively, for pauciarticular JRA and St0.5 values of 10.2 and 10.7 years, respectively, for polyarticular JRA. Sex strongly influenced the age at which many of the alleles have their effect. CONCLUSION: These data define at what age and for how long various HLA alleles influence susceptibility and protection (window-of-effect) in patients with JRA. In addition, these data establish more clearly the boundaries of ages-at-onset for 2 of the subtypes of the disease.

Interaction of HLA phenotype and exposure intensity in sensitization to complex platinum salts.

The development of sensitization to inhaled allergens is determined by the interaction of multiple genetic and environmental influences. Occupational sensitization to low-molecular-weight chemicals allows a specific immunological response to an inhaled hapten to be studied in a well-defined population with characterized exposure. We investigated the workforce of a large platinum refinery exposed to ammonium hexachloroplatinate (ACP) to test the hypothesis that the development of IgE-associated sensitization to ACP was influenced by human leukocyte-associated antigen (HLA) phenotype, especially in those with lower ACP exposure. We performed HLA typing in 44 cases with a positive skin prick test to ACP, and 57 nonsensitized referents matched on age, race, duration of employment, and category of ACP exposure. An HLA-DR3 phenotype was more common among cases (odds ratio [OR] 2.3), and more so in those with low (OR infinite) than with high exposure (OR 1.6); HLA-DR6 was less common among the cases (OR 0.4), an association also stronger in the low-exposure group (OR 0.1 versus 0.5). These results provide evidence that HLA phenotype is a significant determinant of sensitization to complex platinum salts and for the first time show that the strength of this association varies with intensity of exposure to the sensitizing agent. They imply that as exposure-control measures are taken to prevent occupational sensitization and, by analogy, sensitization to allergens outside the workplace, disease incidence will increasingly be determined by genetic susceptibility.

[Study of HLA-II antigens in chronic hepatitis C and B and in acute hepatitis B]. / Estudio de los antígenos HLA-II en las hepatitis crónicas C y B y en las hepatitis agudas B.

The aim of this study was to analyze the variability of the HLA-II system in a series of patients with chronic hepatitis B, chronic hepatitis C and acute hepatitis B to know whether there is any relationship between the polymorphism of the HLA system, the different types of hepatitis and the evolution of the infection. HLA-II antigens were determined by a PCR technique in serum samples of 24 controls, 22 cases of chronic hepatitis C, 38 cases of chronic hepatitis B and 11 with acute hepatitis B. The prevalence of the HLA-DR4 antigen was lower in the cases of chronic hepatitis B (10.5%) and C (13.6%) than in the controls (33.3%), particularly the DRB1*0401 allele (p = NS). The prevalence of HLA-DR6 was similar in chronic hepatitis B (42.1%) and acute hepatitis B (45.5%). Predominance of the DRB1*1301 and DRB1*1302 alleles were, however, observed in acute hepatitis B (36.4%) versus chronic hepatitis B (13%). These data suggest that immunologic factors such as HLA antigens may influence in the susceptibility to infection by HBV and HCV. The use of PCR techniques which discriminate between the different alleles of the HLA antigens may provide better knowledge of the immune response.

Increased frequency of HLA-DR3 and complotype SCO1 in Mexican mestizo children with amoebic abscess of the liver.

The increase of HLA-DR3 and complotype SCO1 previously found in Mexican mestizo adults with E. histolytica amoebic abscess of the liver, was also found in Mexican mestizo children of either sex with the same disease, when compared to the healthy control population (adults and/or children) of the same ethnic and socioeconomic background. This HLA and complotype pattern was not found in Mexican Mestizo patients with amoebic rectocolitis. No linkage disequilibrium was found between these and the other MHC determinants tested in this survey. Thus, HLA-DR3 and SCO1 may constitute primary, independent risk factors, not for any kind of amoebic tissue invasion (i.e. amoebic rectocolitis), but specifically for amoebic liver abscess, irrespective of age or sex. The possibility of linkage disequilibrium with other factors (i.e. the TNF family) within or close to the MHC that were not tested in this study, is discussed. Children with amoebic liver abscess revealed a significant increase in HLA-DR5, and the absence of HLA-DR6 when compared to adults with amoebic liver abscess, suggesting that at least in this ethnic group these class II HLA traits may contribute to some of the peculiarities of pediatric amoebic liver abscess as opposed to the adult version of this disease. HLA-DR3, SCO1, but also HLA-DR5 and HLA-DR6 have all been associated with certain forms of immune-dysfunction, and may thus contribute to some of the clinical and immunological features of this parasitic disease.

Six new DR52-associated DRB1 alleles, three of DR8, two of DR11, and one of DR6, reflect a variety of mechanisms which generate polymorphism in the MHC.

We have sequenced DNA from six new DR52-associated DRB1 alleles initially detected by PCR/SSOP analysis. Three DR8 associated alleles differed from previously known alleles by single nucleotide substitutions. DRB1*0807 and DRB1*0811 both vary from DRB1*08021 at codon 57 resulting in two different amino acids at this residue. DRB1*0807 was identified in samples of Brazilian origin while *0811 was identified among samples from the Tlingit Native American population of Southeast Alaska. DRB1*0814, identified in a family of Chinese origin, differed from DRB1*08032 at codon 12 at both the nucleotide and the amino acid level. In addition, two alleles of DR11, DRB1*1113 and *1119, were each detected in Caucasian individuals. DRB1*1113 differs from other DR11 alleles at codons 37, 67, 70 and 74, while DRB1*1119 differs from *1101 by a single nucleotide substitution at codon 67. Finally, DRB1*1418 was detected in a sample from an Asian or Pacific Islander and shares sequences with several other DR52-associated DRB1 alleles. These six DRB1 alleles appear to have been generated by either gene conversion events, DRB1*1113 and *1418, or by point mutations, DRB1*0814, *0807, *0811 and *1119, although the single nucleotide substitutions found in the latter three alleles are also present in at least one other DRB1 allele and, therefore, could have been the product of gene conversions.

HLA-DR6 (possibly DRB1*1301) is associated with susceptibility to Takayasu arteritis in Mexicans.

Takayasu arteritis is characterized by a "pulseless" condition and occurs frequently in young females from Asian and South American countries. This disease has been found to be linked with major histocompatibility complex (MHC) antigens in Japanese individuals. In the present study we compared gene frequencies of class I, class II, and class III MHC genotypes in patients with Takayasu arteritis and ethnically matched healthy controls. Serological typing was confirmed by molecular typing at the DNA level. We found significant increases in the frequencies of human leucocyte antigen (HLA)-DR6 and HLA-B62 in patients compared to the healthy controls (P corrected [C] = 0.0007, relative risk [RR] = 5.08; PC = 0.05, RR = 3.13 respectively). However, since the number of patients was considerably lower than the number of controls this can be considered as a tendency and not a true association. On the other hand, we found a significantly decreased frequency of HLA-DR4 in patients compared to healthy controls (PC = 0.04, RR = 0.34). At the DNA level, all DR6-positive individuals were HLA-DRB1*1301 whereas controls were HLA-DRB1*1301 (4.2%). Takayasu arteritis in Mexicans is probably associated with the HLA-DR6 (DRB1*1301) gene.

Correlation of peptide specificity and IgG subclass with pathogenic and nonpathogenic autoantibodies in pemphigus vulgaris: a model for autoimmunity.

Pemphigus vulgaris (PV) is a rare, potentially fatal, autoimmune disease that affects the skin and mucous membranes. The PV antigen (PVA) has been characterized as desmoglein 3. PV patients carry HLA-DR4- or HLA-DR6-bearing extended haplotypes. We recently demonstrated that patients with active disease have high titers of PV autoantibodies of the IgG1 and IgG4 subclasses. Patients in remission, healthy unaffected relatives, and some MHC-matched normal individuals have low levels of PV autoantibodies, which are IgG1 only. Furthermore, intraperitoneal injection of IgG from patients with active disease caused clinical disease in mice, but IgG from patients in remission, healthy relatives, or MHC-matched normal individuals did not. We prepared 12 peptides of 30 amino acids each (peptides Bos 1-12) spanning the extracellular domain of PVA. Patients with active disease recognize peptides Bos 1 and Bos 6 with high titers of IgG1 and IgG4 autoantibodies. Patients in remission have IgG1 autoantibodies to peptide Bos 1 only, in statistically significantly lower titers (P < 0.01). They no longer have IgG4 subclass autoantibodies to peptide Bos 6. Healthy relatives and normal unrelated individuals have low levels of only IgG1 autoantibodies that recognize only Bos 1. In vitro studies indicate that Bos 6-specific IgG and, to a lesser extent, Bos 1-specific IgG can cause acantholysis. Our data suggest that Bos 6-specific IgG4 is probably the main acantholytic autoantibody, while Bos 1-specific IgG4 may act as a facilitator or enhancer of the process. In this study we illustrate some of the paradigms that demonstrate the interactions between the MHC, subclass of autoantibodies, and peptide specificities of the autoantibodies in the autoimmune process. Thus, PV provides an important model to study the pathogenesis of autoimmunity.

Irregular polymerase chain reaction-sequence-specific oligonucleotide hybridization patterns reveal seven new HLA-DRB1 alleles related to DR2, DR3, DR6, DR8, and DR11. Implications for sequence-specific priming.

In the past 3 years we have typed over 7000 individuals for HLA-DRB using a nonradioactive PCR-SSO method. The use of locally developed computer programs simplified data input and the interpretation of the DRB PCR-SSO readings. In this way we detected a number of samples with unexpected hybridization patterns. DRB1 exon 2 segments of these samples were amplified, cloned, and sequenced and appeared to identify seven new DRB alleles: DRB1*0304, a DRB1*0301 variant, was observed in three unrelated Caucasoid individuals; DRB1*1606, which is very similar to *1603; DRB1*1113 is a *1101 variant with some *1401 sequences; DRB1*1310 is *1301-like; DRB1*1311 is similar to *1305 and *1307; DRB1*1416 is a *1401 sequence with a HV3 derived from *1301; DRB1*0808 was found in an Ethiopian individual. Next, we studied the effectiveness of PCR-SSP typing of the newly defined DRB1 alleles. Only two variants were distinguished as odd by PCR-SSP and two were typed as regular specificities. Three alleles were not amplified by the primer sets used. As compared to PCR-SSO, the PCR-SSP typing method using currently available typing kits clearly has limitations as far as the recognition of new and variant alleles is concerned. The products of some of these new alleles may be distinguished using conventional serology.

Chronic active autoimmune hepatitis in children. Strong association with a particular HLA-DR6 (DRB1*1301) haplotype.

The association of HLA antigens and type I or "lupoid" CAH-C was investigated in a population of 52 Argentinian Caucasoid patients. When compared with a population of normal individuals of the same ethnic group (n = 197), a significant increase of HLA-DR6 was observed (68.6% in patients vs 17.3% in controls; RR = 12.3, chi 2 = 52.4, pc = 0.00001). DNA typing showed that the HLA-DRB1*1301 allele was present in 32 out of 33 HLA-DR6 patients (66.6% of all the C-CAH patients vs 10.5% in controls; RR = 16.2, chi 2 = 111.3, pc = 0.00001). Analysis of HLA-DQB1 alleles also showed a significant increase of DQB1*0603 (RR = 15.4, chi 2 = 106.5, pc = 0.00001), an allele found in strong linkage disequilibrium with DRB1*1301. The association of CAH-C with this particular HLA-DR6 haplotype has not been previously described for the adult onset CAH. This different HLA predisposition, together with the fact that extrahepatic autoimmune diseases occur frequently only in the adult form of the disease, suggest that the immunopathogenic mechanisms involved in the development of these diseases may be different.