Inhibitory effects of T cells on in vitro granulopoiesis, erythropoiesis, and immunoglobulin production in patients with aplastic anaemia.

Coculture with mononuclear cells from aplastic anaemia (AA) patients and normal bone marrow cells produced different responses among 10 patients studied. In 4 cases, CFU-E growth was inhibited while in another 2 cases CFU-C growth was inhibited. To determine the suppressive effects of mononuclear cells from 6 AA patients, mononuclear cells were separated into T cells, B cells, and monocytes. It was found that T cells from 6 AA patients exhibited suppressive effects on normal CFU-C or CFU-E growth, whereas T cells from normal subjects enhanced the colony formation of CFU-C and CFU-E. On the other hand, monocytes fom 6 AA patients and normal subjects strongly suppressed normal CFU-C and CFU-E growth, although no significant difference was observed in both groups. The immune system in 10 AA patients was evaluated, 3 AA patients (Cases No. 1, 6, 8) exhibited an increase in Tr cells, impairment of PHA responsiveness, and low level of immunoglobulin. T cells from these patients showed a significant suppressive effect on PWM-induced differentiation of allogenic normal B cells. Thus, T cells from 3 out of 10 AA patients exhibited suppressor activities on both haematopoietic cell differentiation and B cell differentiation into plasma cells in vitro.