Lymphocyte subpopulations and lymphokine production in children with constitutional aplastic anemia

The expression of lymphocyte surface markers as well as the production of interleukin-2 (IL-2) and interferon-gamma (IFN) by mitogen-stimulated peripheral blood mononuclear cells (MNC) have been studied in five children with constitutional aplastic anemia. A significantly reduced T4/T8 ratio was found and two of five patients also had a reduced percentage of B cells. One patient had a high percentage of HLA-DR positive T8+ cells, very suggestive of a high degree of circulating activated T suppressor/cytotoxic cells. IL-2 production was reduced in two patients, whereas IFN production was only reduced in one of these. The abnormalities found correlate with the duration of the bone marrow failure. The patients with the longest duration of bone marrow failure also exhibited the lowest T4/T8 ratio. No spontaneous IFN production was detected in any of the patients. There was no clinical benefit or reversal of the immune abnormalities during and following treatment with cimetidine and cyclosporine A in two patients.