CD4 and common variable immunodeficiency: When considering cytokine (IL-10, IL-21, and IL-4) expression by CD4+CXCR5+ T cells (TFH), it was similar in both groups of CVID to that of N. However, when cytokine expression (IL-10 and IL-21) was analyzed in CD4+ T cells that did not express CXCR5, it was significantly higher (p < 0.029) in both CVID groups than in N (Figures 4(a) and 4(b)).