Two-colour flow cytometry study of lymphocyte subpopulations in patients with primary immunodeficiencies

Immunofluorescent flow cytometric examination of one hundred and eighty-five children with different primary immunodeficiency syndromes and sixty-nine control patients revealed twenty-six cases with a bimodal distribution of antigens CD5 and CD7. Such abnormalities were most frequently found in patients with total antibody deficiency, namely those with common variable hypogammaglobulinaemia (10/24 patients) and congenital agammaglobulinaemia with lack of B cells (10/40), but were never seen in normal controls. Two-colour flow immunofluorescence demonstrated that antigen CD4 was expressed only on intensely fluorescent CD5+ cells, irrespective of the immunodeficiency state. Antigen CD4 was detected on cells with both high and low expression of antigen CD7, but a small percentage (2%-5%) of CD4+ lymphocytes did not belong to the CD7+ population. Antigen CD8 was found equally on intensely and weakly fluorescent CD5+ and CD7+ cells. In some immunodeficient patients suffering from ataxia-telangiectasia (12/36) and in some with Wiskott-Aldrich syndrome (2/6) there was a significant excess (greater than 20%) of CD7+ over CD5+ cells. In these patients a considerable number of the CD8+ cells were not part of the CD5+ population, but were always part of the CD7+ population. Cell populations with the phenotype CD5-, CD7+ consisted mainly of lymphocytes showing weak expression of antigen CD8.