With progressive disease, the majority of patients with human immunodeficiency virus (HIV) infection develop bone marrow failure with anemia, leukopenia, and thrombocytopenia, the cause of which has not yet been clarified. Besides direct infection of bone marrow progenitor cells and immune-mediated cytolysis, the action of inhibitory cytokines, like transforming growth factor beta (TGF-beta) and tumor necrosis factor alpha (TNF-alpha), has to be discussed with regard to their pathophysiological role in HIV-induced bone marrow failure. Therefore, the influence of recombinant human TGF-beta and TNF-alpha on colony growth of pluripotent (CFU-GEMM), erythroid (BFU-E), and granulocyte-macrophage (CFU-GM) progenitor cells from the bone marrow of HIV-1-infected persons and normal controls was assessed in methylcellulose cultures. Both cytokines inhibited the colony formation of hematopoietic progenitor cells from HIV-positive persons. When added to unseparated bone marrow cells from HIV-infected persons and normal controls, the 50% inhibition (ID50) of BFU-E by TGF-beta occurred at 1.3 ng/ml and 3.7 ng/ml, respectively, while the ID50 of CFU-GM occurred at 15.5 ng/ml and 142.7 ng/ml. Concentrations of TNF-alpha, causing 50% inhibition of colony formation by bone marrow cells from HIV-infected or noninfected individuals were 6.3 U/ml and 17.0 U/ml for BFU-E, and 24.4 U/ml and greater than 3,000 U/ml for CFU-GM, respectively. The ID50 of the CFU-GEMM growth was below the lowest concentration of both cytokines tested. The suppressive effects were specifically abolished by antibodies against TGF-beta and TNF-alpha, thus confirming that the inhibitory activities were due to the cytokine preparation used.