Response of neutropenia and anaemia to immunosuppressive therapy: report and bone marrow culture studies.

Soft agar culture of bone marrow cells was used to investigate abnormalities of granulopoiesis in a patient with acquired anaemia and neutropenia which responded to immunosuppressive therapy. Results showed that the patient's peripheral blood leucocytes inhibited granulopoiesis in vitro. Variation in the response of different target marrows suggested that inhibition was not due to direct action on granulocyte-monocyte committed stem cells but was directed against or mediated through the cells in target marrow samples which produce granulopoietic stimulators. Cell separation showed that the inhibitory activity was associated with the patient's mononuclear cells rather than neutrophils. A tentative explanation of the mechanism of production of the anaemia is also offered.