Influence of CTLA-4 gene polymorphism in autoimmune and infectious diseases.

Cell-mediated immunity requires costimulatory activity to initiate or inhibit antigen-specific T-cell responses. CTLA-4 is an inhibitory receptor expressed by activated and regulatory T cells. The single nucleotide polymorphism (SNP) +49 A/G of the CTLA-4 gene alters intracellular distribution of CTLA-4, interleukin-2 production, and, as a consequence, T-cell proliferation.

HLA class II and class I polymorphism in Venezuelan patients with myasthenia gravis.

Oligotyping performed among ethnically mixed Venezuelan patients with myasthenia gravis (MG) and controls has revealed positive associations of HLA class I A*31, B*08, B*39, B*40, C*15, C*17, and class II DRB1*09 and negative associations of DQB1*06 and DQA1*02 with the disease. Sequential removal of human leukocyte antigen B (HLA-B) alleles when relative predispositional effects (RPEs) were looked for demonstrated that B*08 is the allele group with the largest contribution in the overall MG patients followed by B*39 and B*40. Several specificities (A*31, B*08, C*17, DRB1*03, DQA1*05, and DQB1*02) indicated increased frequencies among patients with thymic hyperplasia versus patients without hyperplasia or controls.