T-lymphocyte subpopulations in the peripheral blood and bone marrow of patients with aplastic anemia.

A decrease in the absolute number of total lymphocytes, OKT3+ and OKT4+ lymphocytes, and a normal number of OKT8+ lymphocytes were found in the peripheral blood of patients with aplastic anemia. The OKT4:OKT8 ratio was decreased in patients due to a reduction in the percentage of OKT4+ cells and 3 out of 18 patients had a ratio less than 1. The values of the OKT4:OKT8 ratio were not associated either with the severity of the disease or with treatment with androgens. There was no correlation between the OKT4:OKT8 ratio and the number of transfusions received by patients. On the other hand, studies performed with bone marrow lymphocytes showed that the OKT4:OKT8 ratio for both patients and controls was lower than that of the peripheral blood. Since the ratio of OKT4:OKT8 cells in aplastic and control bone marrow was similar no direct pathogenic role can be assigned to the marrow for the imbalance detected in the peripheral blood.