Disturbances of T lymphocyte subsets preceding refractory anemia with excess blasts in transformation in a child

A 5-year-old girl with refractory anaemia with excess of blasts in transformation (RAEBT) terminating in acute nonlymphocytic leukemia is reported. The patient's serum had an inhibitory effect on normal hemopoiesis. T cell subsets defined by monoclonal antibodies revealed a decrease in helper/inducer T cell population (OKT4-positive cells) and inversion of the T4/T8 ratio. It is suggested that imbalance in immunoregulatory T cells, which has a crucial role in the control of hemopoiesis, may be a primary event in the pathogenesis of myelodysplastic syndrome which eventually develops into an overt leukemia.