Besides functional defects, different phenotypical alterations of lymphocytes have been described in patients with CVID. A decrease in LAM-1- (= Leu8) and CD21 expression was observed on B cells. Some patients with CVID show alterations in their T-cell subpopulations: The most striking features of this subgroup are low CD4/CD8-ratio, an increase in CD57/CD8 double-positive lymphocytes, and a strong enhancement of HLA-DR and "memory" markers such as CD29 and LFA-3 on T cells.