Association of complement factor B allotypes and serum biomarkers in rheumatoid arthritis patients and their relatives.

The aim of the study was to investigate the allotypic variability of complement factor B (BF) in patients and relatives with rheumatoid arthritis (RA) and its association with serological biomarkers and clinical features of the disease. BF allotypes were determined by high-voltage agarose gel electrophoresis in serum samples of 180 patients with RA, 198 relatives and 98 controls from Southern Brazil. Anticyclic citrullinated peptide (anti-CCP), antimutated citrullinated vimentin (anti-MCV) and IgA-rheumatoid factor (RF) were determined by ELISA and IgM-RF by latex agglutination in all samples. No significant differences were found in the allotypic variants of BF between patients with RA, relatives and controls, nor associations with gender and age of RA onset. BF*S07 allotype was significantly associated with extra-articular manifestations (EAMs; Secondary Sjögren Syndrome, pneumonitis, rheumatoid nodules) in patients with RA (P = 0.02; OR = 6.62). Patients with phenotype BF F had lower positivity for anti-MCV biomarker (P = 0.02; OR = 0.22) and those with allotype BF*S had higher prevalence of this autoantibody (P = 0.02; OR = 3.77). An increased frequency of RF-IgA was detected in relatives of patients with RA with BF FS07 phenotype (P = 0.02; OR = 7.78). Complement BF variability did not influence the development of RA in the studied patients, but BF variants may act as markers of disease prognosis, such as development of EAMs, corroborating with the role of the alternative pathway in the pathogenesis of RA.

Alotipos del complemento (BF y C4) y haplotipos HLA extendidos en familias venezolanas con diabetes mellitus insulino dependiente / Allotypes of complement (BF y C4) and haplotypes HLA extended in venezuelan family with diabetes mellitus insulin dependent

Se estudiaron 25 familias venezolanas que incluían cada una al paciente y ambos padres, cuyos haplotipos HLA habían sido determinados en el laboratorio. La alotipificación del complemento se realizó por la técnica de electroforésis de alto voltaje (EFAV) en agarosa seguida de inmunofijación con un antisuero específico para el factor B y de EFAV en agarosa seguida de inmunofijación y/o revelado hemolítico en el caso de C4. Se encontró entre nuestros pacientes frecuencia aumentada de manera significativa de alelos clase II, seguidos por clase III y clase I: DR3,DR4,DQW2,BF*F1,C4A*B3BQ,C4*B2,B8,B18 y CW7. Al considerar combinaciones de alelos el mayor riesgo relativo estuvo asociado a heterocigotos DR3/DR4 y al haplotipo B18,BFF1,C4A3B QO/DR3,DQW2. Las asociaciones concuerdan en gran parte con las reportadas para diabeticos causoides del sur de Europa, especificamente para diabeticos españoles, lo cual era de esperarse si se tiene en cuenta que de allí se originó nuestra carga genética caucasoide

Hepatitis B epidemiology and its relation to immunogenetic traits in South American Indians.

Serologic tests for hepatitis B prevalence and immunogenetic characterizations were carried out on a sample of 800 persons from several isolated tribes of the lower Amazon basin and the southern Andes. The prevalence of hepatitis B antigen carriers and of antibody to the surface antigen varied from one tribe to another, but were high in all the forest tribes. The serologic evidence indicated high infection rates early in life, but also an increasing proportion showing evidence of infection with increasing age. The frequency of past infections was not differentially associated with the antigen status of the mother or father. A higher proportion of infected males than females had antigenemia. Contrary to published reports, no association of antigenemia was found with any HLA-A, B or C antigen or immunoglobulin allotype, individually or interactively. Antibody prevalence, however, did differ in persons with different HLA haplotypes.