CD4 and severe combined immunodeficiency: Interestingly, in a recent Eurocord study of children with severe combined immunodeficiency (SCID) transplanted with either UCB (n = 74) or haploidentical grafts (n = 175), there were no significant difference in T-cell recovery (total T cells and CD4+ T cells) between the groups at any time, although the UCB transplant recipients had significantly faster recovery of total lymphocyte counts (34).