Severe combined immunodeficiencies, primary T-cell defects and DiGeorge syndrome in humans: characterization by monoclonal antibodies and natural killer cell activity.

Peripheral blood mononuclear cells from three patients with severe combined immunodeficiency (SCID), three with SCID whether B cell positive or with pure T-cell defect, and two with DiGeorge syndrome were analyzed with a panel of monoclonal antibodies against immature and mature T-cell subsets. Natural killer (NK) cells were enumerated by the use of the HNK-1 monoclonal antibody. NK activity against the K562 and MOLT 4 cell lines was also investigated. According to the monoclonal antibodies profile and the NK activity, patients could be divided into three groups. Patients with classical SCID had no detectable circulating T cells as well as NK cells and activity, probably due to an early block in stem cell differentiation. Patients affected by SCID with B cells or pure T cell defect showed a decrease in lymphocytes with mature phenotypes but prothymocytes or immature thymocytes circulated in peripheral blood. Children with DiGeorge syndrome had a decrease in mature thymocytes and, in this study, NK cells were normal. These data help to clarify both the preeminent immunologic features of SCID and related syndromes and the character of NK cells.