Reduced granulocyte-macrophage colony-stimulating activity by mitogen-stimulated lymphocytes from patients with aplastic anaemia.

The ability of peripheral blood mononuclear cells from patients with idiopathic aplastic anaemia to provide colony-stimulating activity (CSA) was compared to that of normal controls. CSA was prepared by incubating peripheral blood mononuclear cells with phytohaemagglutinin. The supernatant derived from the latter is known as activated lymphocyte-conditioned medium (ALCM). The CSA of ALCM in eight patients was compared to that of normals in 12 experiments. In all but one instance there was decreased CSA by patient ALCM. Possible implications of these findings are discussed.