Lack of impact of cytotoxic T-lymphocyte antigen 4 gene exon 1 polymorphism on susceptibility to or clinical course of egyptian childhood immune thrombocytopenic purpura.

Dysfunctional T-lymphocyte immunity plays an important role in the pathophysiology of immune thrombocytopenic purpura (ITP). Cytotoxic T-lymphocyte antigen 4 (CTLA-4)-a surface marker expressed on T regulatory cells and activated T lymphocytes-is a negative modulator of T-cell responses. Polymorphisms of the CTLA-4 may alter the level of antigen expression and hence may influence immune regulation.