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At least 1,405 records · Page 78Linked to original sources
PubMed1996

Immunogenetics of human IgE.

Immunoglobulin E plays a central role in mediating the pathology of allergic disease. Conversely, it is involved in the normal protective immune responses against parasite infection. Both these biological processes depend on interaction between the variable regions (VH and VL) of IgE antibodies and target antigen. It is now feasible to investigate the molecular nature of VH regions used to encode IgE at the genetic level. Using this technology to analyze IgE in patients with asthma has revealed features which may have relevance for allergic disease. First, preferential choice of VH genes, with dominance of the small VH5 family, particularly the VH32 gene, has been found. This may implicate a B cell superantigen (superallergen) selectively driving the use of these genes. Second, VH5 genes in IgE are somatically mutated with clear hot spots of mutational activity. Mutational hotspots, which are a feature of the VH5 gene, are supplemented in IgE by ongoing mutations which may be involved in affinity maturation. Third, a single B cell can switch to either IgE or IgG4, with both variants coexisting in blood. These findings may provide clues to the mechanism by which IgE is generated, and suggest options for therapeutic intervention.

Amino Acid Sequence↗
PubMed1997

[Immunohistochemical and immunogenetic analysis of ocular adnexal lymphoid proliferations].

We examined 20 cases (21 specimens) of ocular adnexal lymphoid proliferations, using the histological, immunohistochemical and molecular genetic methods. The latter two protocols were performed to detect the light chains restriction of immunoglobulin with peroxidase-antiperoxidase (PAP) methods, and the clonality of immunoglobulin heavy chain gene with the hemi-nested polymerase chain reaction (PCR) method, respectively. Although in 8 cases it could not be morphologically determined whether they were neoplastic or not, clonality was revealed in 1 case with immunohistochemistry and in 4 cases with PCR. Two cases showed discordant results between immunohistochemistry and PCR probably due to somatic mutation of the framework region of the immunoglobulin heavy chain gene. Therefore, we, concluded that examination with these methods contribute to a better understanding of the nature of the ocular adnexal lymphoid proliferations. Furthermore, the immunoglobulin gene PCR method is very useful in practical examination, as it can be used with formalin-fixed paraffin-embedded specimens.

Adult↗
PubMed1996

[Insulin-dependent diabetes mellitus in Santiago, Chile: the role of immunogenetic and environmental factors].

The role of HLA class II alleles in the genetic susceptibility to develop insulin-dependent diabetes mellitus (IDDM) was examined by means of PCR and oligospecific probes in 63 IDDM children and 74 controls subjects. In diabetic patients we found a significant increase in the alleles frequency DR3, DR4, DQB1*0302 and DQA1*0301 compared to the control group, where the most prevalent alleles were DR2, DR14 (DRB1*1402), DQA1*0101 and DQA1*0201. All the risk genotypes in the diabetic group were similar than in other caucasian groups: DR3/DR4-DQB1*0201/0302-DQA1*0301/0501 and DR4/DR4-DQB1*0302/0302-DQA1*0301/0301. The homozygote character no asp57 conferred an absolute risk (AR) of 3.87 and the marker Arg52 an AR of 5.78/100.000 bab year. The homozygosis for both markers (no Asp57 + Arg52) had an AR of 7.56/100.000 bab year. Regarding environmental factors associated with IDDM, our population under study showed a low prevalence of infectious agents (mainly mumps and rubella, specifically associated with IDDM) and a high prevalence of effective breast-feeding (over 3 months). These factors could be exercising a protector role in the development of IDDM. The factors that appear to be important in the low incidence of IDDM in Santiago de Chile are: the low prevalence of infectious agents related to IDDM, the high percentage of breast-feeding children in the population, the reduced frequency of susceptible molecules as DR3, DQB1*0201 (compared to other caucasian groups) and the presence of protective genotypes related to DR13 and DR14 observed in the non diabetic children.

Adolescent↗
PubMedDate not supplied

[Immunogenetic study in a case of DiGeorge syndrome].

DiGeorge Syndrome is a congenital immunodeficiency characterized clinically by hypocalcemic tetany, congenital heart disease, unusual facies, and increased susceptibility to infection. Pathologically, the syndrome is marked by the abscence or hipoplasia of the thymus and parathyroid glands as well as cardiac or aortic arch abnormalities. Most patients show partial or complete T cell immunodeficiency and normal or near-normal B-cell immunity. A review is made on a clinical case of DiGeorge syndrome is presented. A 52 days old boy, was admitted through emergency. There was no familial evidence of alcoholism or immunodeficiency. He showed irritability due to hypocalcemia. The examination revealed facial and cardiovascular abnormalities and the immunological investigation revealed hypogammaglobulinemia, deficiency of the cell, CD4 and CD8 decreased and with inverted relation. Chest X ray showed cardiomegaly grade II, and no thymus was seen. The diagnosis of the complete DiGeorge syndrome was based on the abnormalities found.

Abnormalities, Multiple↗
PubMedDate not supplied

[Immunogenetic study in Mexican couples with recurrent spontaneous abortions].

AIM: To study the HLA markers in Mexican couples who have suffered three or more spontaneous abortions. DESIGN: The study included 24 couples with recurrent abortions and 32 with normal fertility. METHOD: HLA class I (A, B, C) and class II (DR, DQ) typing was done with a standard microlymphocytoxity test. The intergroup differences were evaluated by chi-square and the Fisher exact test. RESULTS: The frequency of the MHC markers in the males and females of couples with abortions were not significantly different from those in fertile couples. However, the abortion couples shared class I antigens more often than expected from random mating as compared to fertile couples, specially in the HLA-B locus. We also found a significantly decreased frequency of the HLA-B7 antigen in males belonging to the abortion group. CONCLUSION: These results suggest that HLA-B antigens may be markers for genes related to pregnancy outcome in Mexicans.

Abortion, Habitual↗
PubMed1998

Advances in the immunogenetics of coeliac disease. Clues for understanding the pathogenesis and disease heterogeneity.

Recent studies using the technique of the human genome screening in families with multiple siblings suffering from coeliac disease have suggested the presence of at least four different chromosomes in the predisposition to suffer from coeliac disease. Two loci in chromosome 6 appear to be important in disease susceptibility. Other studies based on cytokine gene polymorphisms have found a strong association with a particular haplotype in the TNF locus. This haplotype carries a gene for a high secretor phenotype of TNFalpha. The finding may be important in understanding the heterogeneity of inflammatory response. Evidence has been presented in favour of a predominantly Th1 pattern of cytokine production by the coeliac disease associated HLA-DQ restricted T cell clones. HLA-DQ2 and -DQ8 restricted gliadin-specific T cells have been shown to produce IFN-gamma, which appears to be an indispensable cytokine in the damage to enterocytes encountered in the small intestine, since the histological changes can be blocked by anti-IFN-gamma antibodies in vitro. TNF-alpha, also produced by several T cell clones, may in conjunction with IFN-gamma have a toxic effect or enhance the IFN-gamma-induced increase of HLA-class II expression on surface enterocytes. In the lamina propria this leads to an increased expression of adhesion molecules such as ICAM-1 on T lymphocytes and macrophages. Th1 cells also activate cytotoxic CD8+ T cells that migrate in the epithelial layer, and stimulate further LPL macrophages to produce IFN-gamma and TNF-alpha enhancing the inflammatory response. During this process autoreactive T cells proliferate, creating a situation which is very similar to the process that takes place in autoimmune diseases. Occasionally, this inflammatory destruction of the small intestinal integrity initiated by gluten peptides goes further and develops into a proper autoimmune disease which requires the use of immunosuppressive drugs in addition to a gluten-free diet.

Celiac Disease↗
PubMed1998

Immunogenetic studies in families of children with juvenile dermatomyositis.

OBJECTIVE: We reported an association between juvenile dermatomyositis (JDMS) and the HLA-DQA1*0501 allele. The purpose of this study was to determine whether there is evidence for linkage between JDMS and the DQA1*0501 allele in JDMS families. METHODS: The study population included 18 unrelated patients with JDMS, their parents, and 49 unaffected siblings. Using molecular genetic techniques, we studied the HLA genes, DRB1, DQA1, and tumor necrosis factor-alpha. RESULTS: Using the transmission disequilibrium test, we confirmed our earlier observations that the HLA-DQA1*0501 allele confers primary susceptibility to JDMS. CONCLUSION: DQA1*0501 confers genetic risk for JDMS; we cannot exclude the effects of alleles at other linked loci that were not studied or interactive effects between DQA1 alleles and alleles at other loci.

Alleles↗
PubMedDate not supplied

[Results of immunogenetic typing of lymphocytes of patients with keratoconus].

Histotyping of HLA I antigens in 100 patients with keratoconus. Europeoids of the Chelyabinsk district, and of 701 controls (donors listed in the regional register) showed an increased incidence of HLA A28, B12, and B15, a decreased incidence of HLA B8, B13, and complete absence of HLA A11. Estimation of HLA haplotypes in keratoconus showed an increased incidence of haplotypes A1-B5 (relative risk RR = 5.9), A2-B15 (RR = 3.34), A2-B27 (RR = 2.12), and A9-B21 (RR = 4.13) and decreased incidence of A1-B8 (RR = 0.31). The incidence of incomplete phenotypes was 27%. The most incident of incomplete phenotypes was A3-B35. Reliably linked HLA haplotypes A3-B7, A2-B27, A9-B21, and A9-B35 were typical of men with keratoconus, whereas A2-B21 haplotype was characteristic of the female patients.

Adult↗
PubMedDate not supplied

Anti-neutrophil cytoplasmic antibodies in 566 European patients with systemic lupus erythematosus: prevalence, clinical associations and correlation with other autoantibodies. European Concerted Action on the Immunogenetics of SLE.

OBJECTIVES: To evaluate, in a cohort of 566 patients with systemic lupus erythematosus (SLE) drawn from 11 European centres: (i) the prevalence of ANCAs and their subspecificities in a large series of European SLE patients; (ii) the possible associations of ANCA with the most common clinical manifestations of the disease; and (iii) whether ANCAs correlate with some of the autoantibodies commonly found in SLE. METHODS: ANCA detection was performed by indirect immunofluorescence (IIF), and by ELISA for lactoferrin (LF), myeloperoxydase (MPO), proteinase3 (PR3) and lysozyme (LZ) subspecificities. RESULTS: The prevalence of ANCA was 16.4% (IIF). The prevalence of LF was 14.3%, LZ 4.6%, MPO 9.3%, and PR3 1.7%. Our results show that ANCA is associated with certain clinical manifestations of SLE. In particular, positive correlations were found between IIF ANCA and serositis (p = 0.026), livedo reticularis (p = 0.01), venous thrombosis (p = 0.03) and arthritis (p = 0.04), while anti-LF antibodies were associated with serositis (p = 0.05) and livedo reticularis (p < 10(-3). Nevertheless, multivariate analysis demonstrated that other autoantibodies, such as aCL and SSA/Ro, are more closely correlated than ANCA with some of the aforementioned clinical features. CONCLUSION: Our results demonstrate that ANCA are detectable in SLE sera and that some of them are associated with particular clinical manifestations. Whether ANCA plays a direct pathogenetic role in the vascular damage of SLE or only represents an epiphenomenon or a marker of disease activity remains to be elucidated.

Adolescent↗
PubMedDate not supplied

Association of 16/6 and SA1 anti-DNA idiotypes with anticardiolipin antibodies and clinical manifestations in a large cohort of SLE patients. European Concerted Action on the Immunogenetics of SLE.

OBJECTIVE: The SA1 and 16/6 idiotypes can be found in some patients with systemic lupus erythematosus (SLE) or anti-phospholipid syndrome (APS). The aim of this study was to ascertain the prevalence of these idiotypes in a large cohort of SLE patients, and to determine whether their presence is correlated with the anticardiolipin (aCL) and anti-dsDNA antibodies or with the clinical manifestations of SLE. METHODS: 492 SLE patients were evaluated for clinical manifestations of SLE and were assigned a disease severity score. ds-DNA autoantibodies, aCL autoantibodies of the IgM, IgG and IgA isotypes, and SA1 and 16/6 idiotypes were also determined in these patients. RESULTS: The prevalence of the SA1 and 16/6 idiotypes in the 492 SLE patients was found to be 11% and 5.1%, respectively, and these idiotypes were significantly more prevalent in the patients who had aCL antibodies of either the IgG, IgM or IgA isotypes. Moreover, while the 16/6 idiotype was not associated with the clinical manifestation of either SLE or APS, the SA1 idiotype was found significantly more frequently in patients who had vascular events Raynaud's phenomenon or hemolytic anemia (p = 0.016, 0.01, 0.01, respectively). CONCLUSION: SLE patients with the SA1 idiotype may run a higher risk of developing vascular events, Raynaud's phenomenon or hemolytic anemia. These clinical manifestations can be attributed to both SLE and secondary APS when aCL autoantibodies are also found. These results indicate that the possible pathogenicity of certain idiotypes in SLE cannot be excluded.

Adolescent↗