CD4 and common variable immunodeficiency: Among T cells, most frequently, low numbers of total CD4 + T helper cell subsets, essential for effective B cell response and antibody production [33, 35], followed by deficiency of CD3 + CD4 + CD45RA + naïve T cells and CD3 + CD4 + CD45RA + CD31 + recent thymic emigrants were reported in pediatric CVID [33].