Absence of the tag polymorphism for the risk haplotype HLA-DR2 for multiple sclerosis in Wixárika subjects from Mexico.

The HLA-DRB1*15:01 allele has a demonstrated risk for the development of multiple sclerosis (MS) in most populations around the world. The single nucleotide polymorphism (SNP) rs3129934 is found in linkage disequilibrium with the risk haplotype formed by the HLA-DRB1*15:01 and HLA-DQB1*06:02 alleles, and it is considered a reliable marker of the presence of this haplotype. Native Americans have a null or low prevalence of MS. In this study, we sought to identify the frequency of rs3129934 in the Wixárika ethnic group as well as in Mestizo (mixed race) patients with MS and in controls from western Mexico. Through real-time polymerase chain reaction (PCR) using TaqMan probes, we analyzed the allele and genotype frequencies of rs3129934 in Mestizo individuals with and without MS and in 73 Wixárika subjects from the state of Jalisco, Mexico. The Wixárika subjects were homozygote for the C allele of rs3129934. The allele and genotype frequency in Mestizos with MS was similar to that of other MS populations with Caucasian ancestry. The absence of the T risk allele rs3129934 (associated with the haplotype HLA-DRB1*15:01, HLA-DQ1*06:02) in this sample of Wixárika subjects is consistent with the unreported MS in this Amerindian group, related to absence of such paramount genetic risk factor.

The meaning of anti-Ro and anti-La antibodies in primary Sjögren's syndrome.

Anti-SSA/Ro and anti-La/SSB are the hallmark antibodies in primary Sjögren's syndrome (pSS), being present in 60-70%. These antibodies have been associated with an earlier disease onset, glandular dysfunction and extraglandular manifestations as well as with other B cells activation markers. In addition an immunogenetic background is important for the autoantibody formation, having a stronger association with HLA-DR2 and HLA-DR3. Anti-Ro/SSA and anti-La/SSB antibodies are useful in the diagnosis of pSS and help to identify more "active" patients, however their association with response to treatment is unclear. Herein we review the evidence regarding the association of these antibodies with HLA background, demographic, clinical, glandular dysfunction, other serologic features and response to treatment in patients with pSS.

Use of human bronchial epithelial cells (BEAS-2B) to study immunological markers resulting from exposure to PM(2.5) organic extract from Puerto Rico.

Fine particulate air pollutants, mainly their organic fraction, have been demonstrated to be associated with cardiovascular and respiratory health problems. Puerto Rico has been reported to have the highest prevalence of pulmonary diseases (e.g., asthma) in the United States. The aim of this study was to assess, for the first time, the immunological response of human bronchial epithelial cells (BEAS-2B) to organic extracts isolated from airborne particulate matter (PM(2.5)) in Puerto Rico. Organic extracts from PM(2.5) collected throughout an 8-month period (2000-2001) were pooled (composite) in order to perform chemical analysis and biological activity testing. BEAS-2B cells were exposed to PM(2.5) organic extract to assess cytotoxicity, levels of cytokines and relative gene expression of MHC-II, hPXR and CYP3A5. Our findings show that organic PM(2.5) consist of toxic as well as bioactive components that can regulate the secretion of cytokines in BEAS-2B, which could modulate inflammatory response in the lung. Trace element analyses confirmed the presence of metals in organic extracts highlighting the relative high abundance of Cu and Zn in polar organic extracts. Polar organic extracts exhibited dose-dependant toxicity and were found to significantly induce the release of interleukin 6 (IL-6), IL-1beta and IL-7 while significantly inhibiting the secretion of IL-8, G-CSF and MCP-1. Moreover, MHC-II transcriptional activity was up-regulated after 24 h of exposure, whereas PXR and CYP3A5 were down-regulated. This research provides a new insight into the effects of PM(2.5) organic fractions on specific effectors and their possible role in the development of respiratory inflammatory diseases in Puerto Rico.

Does the DRB1*1501 allele confer more severe and faster progression in primary progressive multiple sclerosis patients? HLA in primary progressive multiple sclerosis.

The effect of HLA alleles on the outcome of multiple sclerosis (MS) has been widely investigated; however, results are conflicting and no consistent correlation has been established. This study evaluated the association between the HLA DR2 haplotype in patients with primary progressive MS (PPMS) and the effect of alleles on progression. An association was found between PPMS and the DR2 and DRB1*1501 and DQB1*0602 alleles. Severe morbidity was found in DRB1*1501-positive PPMS patients. This exploratory study raises new hypotheses for future research and emphasizes the need to investigate possible candidate genes other than HLA that may contribute towards heterogeneity in the course of the disease.

[Comparative study between the Mitsuda test and the human leukocyte antigens in leprosy patients]. / Estudo comparativo entre reação de Mitsuda e antígenos leucocitários humanos em pacientes hansenianos.

In this study, we aimed to compare the Mitsuda skin test with the alleles HLA-DR2/HLA-DR3 and HLA-DQ1, in relation to the clinical forms of leprosy in 176 patients (50 TT, 50 LL and 76 B). The results obtained did not reveal any association between the Mitsuda reaction and the HLA alleles in the clinical forms isolated. However, when analyzed according to Mitsuda test response, a significant association was found between patients with negative Mitsuda reaction and HLA-DQ1 (p=0.002). No association was observed between positive Mitsuda reaction and the HLA-DR2/DR3 alleles. We concluded that the allele HLA-DQ1 has an important participation when there is no response to the Mitsuda test. We suggest that more specific studies should be developed on this allele.

T cell epitope characterization in tandemly repetitive Trypanosoma cruzi B13 protein.

Proteins containing tandemly repetitive sequences are present in several immunodominant protein antigens in pathogenic protozoan parasites. The tandemly repetitive Trypanosoma cruzi B13 protein is recognized by IgG antibodies from 98% of Chagas' disease patients. Little is known about the molecular mechanisms that lead to the immunodominance of the repeated sequences, and there is limited information on T cell epitopes in such repetitive antigens. We finely characterized the T cell recognition of the tandemly repetitive, degenerate B13 protein by T cell lines, clones and PBMC from Chagas' disease cardiomyopathy (CCC), asymptomatic T. cruzi infected (ASY) and non-infected individuals (N). PBMC proliferative responses to recombinant B13 protein were restricted to individuals bearing HLA-DQA1*0501(DQ7), -DR1, and -DR2; B13 peptides bound to the same HLA molecules in binding assays. The HLA-DQ7-restricted minimal T cell epitope [FGQAAAG(D/E)KP] was identified with an overlapping combinatorial peptide library including all B13 sequence variants in T. cruzi Y strain B13 protein; the underlined small residues GQA were the major HLA contact residues. Among natural B13 15-mer variant peptides, molecular modeling showed that several variant positions were solvent (TCR)-exposed, and substitutions at exposed positions abolished recognition. While natural B13 variant peptide S15.9 seems to be the immunodominant epitope for Chagas' disease patients, S15.4 was preferentially recognized by CCC rather than ASY patients, which may be pathogenically relevant. This is the first thorough characterization of T cell epitopes of a tandemly repetitive protozoan antigen and may suggest a role for T cell help in the immunodominance of protozoan repetitive antigens.

Estudios genéticos y ambientales en el lupus eritematoso sistémico / Genetic and environmental studies in systemic lupus erythematosus

The cause of systemic lupus erythematosus (SLE) remains rather poorly understood. Accumulating reported evidence suggests that both environmental and genetic factors play a part. They somehow create an abnormal CD4 T-cell driving force which results in autoantibody production. We present a synthesis of previously published study. The objective of our original study was to examine the role of genetic and environmental factors in 26 families having two or more members of SLE. The role of genetic factors was examined by determining the HLA of each individual in the study. No association between SLE and HLA-A, B, C antigens was found. There was however, a significant association with HLA-DR2 in white subjects with SLE. The most striking finding was that HLA sharing was increased among the affected members, suggesting genetic similarities. Seven of 14 sib pairs (50%) who had concordant SLE were HLA identical as opposed to an expected 25%. The role of environmental factors was examined by determining lymphocytotoxic antibodies (LCA) in patients and their consanguineous and non-consanguineous relatives. Interestingly 15/18 (83%) patients with SLE and 11/22 (50%) consanguineous relatives had LCA, while 1/9 (11%) spouses and 2/42 (5%) healthy controls had these antibodies. We conclude that genetic factors have a role in the development and expression of SLE. Environmental factors may trigger the disease in genetically susceptible individuals.

La causa del lupus eritematoso sistémico (LES) continúa con deficiente comprensión hasta el momento actual. Abundan los datos publicados en el sentido de que tanto los factores ambientales como los genéticos cumplen cierta función en su desarrollo. De algún modo actúan induciendo la producción de células T tipo CD4 anormales, responsables a su vez de la producción de un autoanticuerpo. Presentamos la síntesis de un estudio que hemos publicado recientemente. El objetivo de nuestra investigación original fue examinar el papel de los factores genéticos y ambientales en 26 familias con dos o más miembros enfermos de LES. La participación del componente genético fue analizada a través de la determinación del HLA de cada individuo incluido en el estudio. No se encontró relación alguna entre LES y los antígenos HLA-A, B, C. Sin embargo, hubo una asociación significativa con HLA-DR2 en individuos de raza blanca con esta enfermedad del tejido conectivo. El hallazgo más notorio fue que la participación del HLA era mayor entre los miembros afectados, señal de la existencia de similitudes genéticas. Siete de 14 pares de allegados consanguíneos (50%) que poseían LES concordante eran HLA idénticos, a diferencia del 25% que en realidad se esperaba. El papel de los factores ambientales se analizó determinando los anticuerpos antilinfocitotóxicos (ALT) en los pacientes y en sus familiares consanguíneos y no consanguíneos. En forma llamativa, 15 de 18 individuos con LES (83%) y 11 de 22 familiares consanguíneos (50%) tenían ALT, mientras que sólo 1 de 9 cónyuges (11%) y 2 de 42 controles sanos (5%) eran portadores de estos anticuerpos. Concluimos que los factores genéticos desempeñan un papel en el desarrollo y la expresión del LES. Los factores ambientales pueden actuar como desencadenantes de la enfermedad en individuos genéticamente susceptibles.

Analysis of human leukocyte antigens class II-DR in Brazilian children and adolescents with systemic lupus erythematosus

OBJECTIVE: To analyze the frequency of human leukocyte antigens class II-DR in children and adolescents with systemic lupus erythematosus. PATIENTS AND METHODS: Fifty-fiveBrazilian systemic lupus erythematosus children and adolescents and 308 healthy individuals were studied. Gender, race, and age of onset of systemic lupus erythematosus were recorded. The human leukocyte antigens typing of class II-DR was carried out by polymerase chain reaction amplification with sequence-specific primers (PCR-SSP). Data were analyzed statistically using the chi square test with Yates' correction, Fisher's exact test, and Bonferroni's correction. RESULTS: Human leukocyte antigen-DR 15 was the most frequently detected antigen in this group of children and adolescents, and it also occurred more frequently in the female group, in children with onset of systemic lupus erythematosus between 0 and 9 years and between 10 to 14 years, and in the Black race group, but these associations were not statistically significants. CONCLUSION: In this group of children and adolescents with a high degree of racial admixture, we could not verify a significant association between human leukocyte antigens class II-DR and systemic lupus erythematosus

Analysis of human leukocyte antigens class II-DR in Brazilian children and adolescents with systemic lupus erythematosus.

OBJECTIVE: To analyze the frequency of human leukocyte antigens class II-DR in children and adolescents with systemic lupus erythematosus. PATIENTS AND METHODS: Fifty-fiveBrazilian systemic lupus erythematosus children and adolescents and 308 healthy individuals were studied. Gender, race, and age of onset of systemic lupus erythematosus were recorded. The human leukocyte antigens typing of class II-DR was carried out by polymerase chain reaction amplification with sequence-specific primers (PCR-SSP). Data were analyzed statistically using the chi square test with Yates' correction, Fisher's exact test, and Bonferroni's correction. RESULTS: Human leukocyte antigen-DR 15 was the most frequently detected antigen in this group of children and adolescents, and it also occurred more frequently in the female group, in children with onset of systemic lupus erythematosus between 0 and 9 years and between 10 to 14 years, and in the Black race group, but these associations were not statistically significants. CONCLUSION: In this group of children and adolescents with a high degree of racial admixture, we could not verify a significant association between human leukocyte antigens class II-DR and systemic lupus erythematosus.

Polymorphism and distribution of HLA-DR2 alleles in Mexican populations.

DRB1*15/16 nucleotide polymorphism was analyzed in 68 DR2 positive individuals (18 Mexican Mestizos, 30 Mazatecans and 20 Nahuas), carrying a total of 75 DR2 haplotypes. HLA-DR2 was one of the most frequent specificities detected in Mazatecans and Nahuas with gene frequency (gf) of 0.232 and 0.141, respectively. In these populations DRB1*16 was the most frequent DR2 split (gf = 0.183 in Mazatecans and gf = 0.135 in Nahuas), whereas in Mexican Mestizos the most frequent was DRB1*15 (gf = 0.065). Four DRB1-DQB1 combinations in Mexican Mestizos, two in Mazatecans and one in Nahuas were in linkage disequilibrium. In spite of the restricted polymorphism, there were differences on DRB1*15/16 alleles found in Mexicans. DRB1*1501 a Caucasian allele was predominant in Mexican Mestizos, whereas DRB1*1602 an Amerindian allele was characteristic on Indian populations. An important difference was detected among the Amerindian populations studied since DRB1*1502 was only present in Mazatecans. This data corroborates the restricted polymorphism of DRB1*15/16 and the high frequency of DRB1*16 subtype in autochthonous American populations and suggest that the differences in gene frequencies of DRB1*15/16 alleles could be helpful in distinguishing each of these population.

HLA class II genotypes in Mexican Mestizos with familial and nonfamilial multiple sclerosis.

Predisposition to MS is associated with the HLA-DR2 antigen in white patients. The authors investigated the genetic factors behind the increasing frequency of MS in the Mexican population. HLA-DR and DQ were analyzed in 17 patients with MS, 15 of their first-degree relatives, and 99 healthy ethnically matched controls. DR2 or DR3 was found in 15 of 17 patients. In controls, both alleles had frequencies less than 0.05. MS in Mexican patients was associated with HLA-DR2 and DR3.

Association of Alport's syndrome with HLA-DR2 antigen in a group of unrelated patients.

A few family studies have evaluated HLA antigens in Alport's syndrome; however, there are no large population studies. In the present report, we studied 40 unrelated white patients with Alport's syndrome seen at the Unit of Renal Transplantation, Faculty of Medicine of Ribeirão Preto, São Paulo, Brazil. HLA-A, -B, -DR and -DQ antigens were typed using a complement-dependent microlymphocytotoxicity assay. A control white population (N = 403) from the same geographical area was also typed for HLA antigens. Although the frequencies of HLA-A and -B antigens of patients were not statistically different from controls, the frequency of HLA-DR2 antigen observed in patients (65%) was significantly increased in relation to controls (26%; P < 0.001). The relative risk and etiologic fraction for HLA-DR2 antigen were 5.2 and 0.525, respectively. Although few immunological abnormalities have been shown in Alport's syndrome, in this report we emphasize the association of HLA molecules and Alport's syndrome. Besides the well-known inherited molecular defects encoded by type IV collagen genes in Alport's syndrome, the major histocompatibility alleles may be in linkage disequilibrium with these defective collagen genes.

C2 deficiency in blood donors and lupus patients: prevalence, clinical characteristics and HLA-associations in the Brazilian population.

The objective of the present study was to investigate the prevalence, clinical characteristics, and HLA association of C2 deficiency in the Brazilian population. The frequency of C2 deficiency profile (C2Q degree profile) was 2.2% among 1503 blood donors and 6.6% among 166 patients with systemic lupus erythematosus (SLE). A higher incidence of clinical manifestations possibly related to immune complex disease was observed among blood donors with C2Q degree profile and their relatives with C2Q degree profile when compared to the normal C2 relatives. The comparison of clinical and laboratory features between SLE patients with C2Q degree profile and those with normal C2 revealed earlier disease onset, higher frequency of oral ulcerations and lower frequency of anti-native DNA antibodies in the first group. The HLA study conducted on 18 individuals with C2Q degree profile (11 blood donors and 7 SLE patients) confirmed the previously reported association with the antigens HLA-A25, B18 and DR2, supporting the concept that probably most C2 deficiency cases, throughout the world, are due to a single mutation in the C2 gene in linkage disequilibrium with the A25B18DR2 haplotype.

Association of leprosy with HLA-DR2 in a Southern Brazilian population.

The association between HLA specificities and leprosy was investigated in a southern Brazilian population. One hundred and twenty-one patients and 147 controls were typed for HLA-A, B, Cw, DR and DQ. Patients were subdivided into the following subgroups, according to clinical, histological and immunological criteria: lepromatous (N = 55), tuberculoid (N = 32), dimorphous (N = 20), and indeterminate (N = 14). The frequencies of HLA specificities were compared between the total group of patients and controls, and between the same controls and each subgroup of patients. After correction of the probabilities, deviations, were not significant, except for the DR2 specificity, which presented a frequency of 44.2% in the total group of patients and 56.3% in the subgroup of individuals with the tuberculoid form of the disease, compared to 23.3% in the controls. Stratified analysis showed that the increased DR2 frequency in the total group of patients was due to the subgroups with tuberculoid and dimorphous forms. The relative risk of tuberculoid leprosy for DR2-positive individuals was 4.2, and the etiologic fraction of DR2 was 0.429. In conclusion, a positive association of the DR2 specificity with the tuberculoid form of leprosy, but not with the lepromatous, dimorphous, or indeterminate forms, was demonstrated in this Southern Brazilian population.

Association of leprosy with HLA-DR2 in a Southern Brazilian population

The association between HLA specificities and leprosy was investigated in a Southern Brazilian population. One hundred and twenty- one patients and 147 controls were typed for HLA-A, B, Cw, DR and DQ. Patients were subdivided into the following subgroups, according to clinical, histological and immunological criteria: lepromatous (N = 55), tuberculoid (N = 32), dimorphous (N = 20), and indeterminate (N = 14). The frequencies of HLA specificities were compared between the total group of patients and controls, and between the same controls and each subgroup of patients. After correction of the probabilities, deviations were not significant, except for the DR2 specificity, which presented a frequency of 44.2 per cent in the total group of patients and 56.3 per cent in the subgroup of individuals with the tuberculoid form of the disease, compared to 23.3 per cent in the controls. Stratified analysis showed that the increased DR2 frequency in the total group of patients was due to the subgroups with the tuberculoid and dimorphous forms. The relative risk of tuberculoid leprosy for DR2-positive individuals was 4.2, and the etiologic fraction of DR2 was 0.429. In conclusion, a positive association of the DR2 specificity with the tuberculoid form of leprosy, but not with the lepromatous, dimorphous, or indeteterminate forms, was demonstrated in this Southern Brazilian population.

Frequency of HLA antigens in a Brazilian type I diabetic population.

1. Sixty-five Brazilian, patients with type I, insulin-dependent diabetes mellitus (IDDM) and 100 unaffected individuals were typed for HLA-A, -B, -C and DR antigens. 2. A significantly higher frequency of HLA-A2 (48% of the patients versus 21% of the controls), B15 (20% of the controls), DR3 (57% of the patients versus 28% of the controls) and DR4 (54% of the patients versus 23% of the controls) was found for IDDM patients compared to the controls. 3. In contrast, DR2 (11% of the patients versus 31% of the controls) and DR7 (3% of the patients versus 21% of the controls) were lower in diabetics, but the difference was not significant. 4. The data reported here, when compared with those of other studies, emphasize the ethnic variability in HLA-IDDM associations.