HLA-C and infection: It has been reported that abnormalities in thymi and T-cell generation after cyclosporine administration are observed [13]. For example, cyclosporine causes involution of the thymic medulla [13], decreased single-positive thymocytes and peripheral T cells, and downregulated expression of class II MHC [14]. Then, abnormalities in thymi and T-cell generation in the presence of calcineurin inhibitors may provide an explanation for the increased risk of infection.