The modulation of growth of normal and leukemic myeloid progenitor cells in soft agar cultures by recombinant human tumor necrosis factor-alpha (TNF alpha) and recombinant human interferon-gamma (IFN gamma) was investigated. TNF alpha inhibited colony formation of all colony types representing different maturational stages of normal progenitor cells committed to the myeloid lineage with different orders of sensitivity. Blast-type colonies derived from patients with acute myelogenous leukemia were more sensitive to TNF alpha inhibition than progenitor cells purified from normal bone marrow or bone marrow from patients with stable-phase chronic myelogenous leukemia. The response of most colony types to IFN gamma was poor. However, when IFN gamma was administered together with TNF alpha, synergistically enhanced antiproliferative effects were detected in all colony types tested. The antiproliferative action of IFN gamma on myelopoiesis was enhanced in culture by the presence of autologous monocytes, presumedly by inducing endogenous production of TNF alpha. However, TNF alpha seemed to act directly on the progenitor cells themselves to suppress their clonal growth, rather than involving accessory marrow elements such as monocytes and/or T lymphocytes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.