Expression of CD152 (CTLA-4) in children with autoimmune thyroiditis and +49 A/G polymorphism of exon 1 of the CTLA-4 gene.

CTLA-4 gene is one of the strongest locus of genetic susceptibility to autoimmune thyroid diseases. The aim of the present study was to investigate surface expression of CTLA-4 on peripheral T cells in homozygotes AA and GG at position +49 of CTLA-4 gene in children with Hashimoto's thyroiditis and in healthy controls. Blood samples were obtained from 100 children: 45 with Hashimoto's thyroiditis and 55 controls. CTLA-4 exon 1 polymorphism was defined by SSCP and RFLP with BbvI enzyme. T cells were analyzed with three color flow cytometry by Coulter EPICS XL. We found that CTLA-4 expression was significantly lower in the thyroiditis patients than in controls, but CTLA-4 expression in homozygotes GG and AA was comparable. We therefore conclude that decreased expression of CTLA-4 on T cells in children with Hashimoto's thyroiditis is not dependent on polymorphic changes at position +49 of CTLA-4 gene.