Secretion of an interleukin 1-like activity by acute monocytic leukemia cells which inhibits growth of fibroblasts.

Acute monocytic leukemia cells (AMoL cells), obtained by leukapheresis, were cultured in vitro. In response to lipopolysaccharide, AMoL cells produced a large amount of thymocyte proliferation activity. The crude supernatants from AMoL cells inhibited fibroblast growth, in a dose-dependent manner. Upon gel filtration, the thymocyte proliferation activity had a molecular mass of 37,000 and 17,000 daltons, and was heat labile and fairly resistant to freezing and thawing. The fractions containing thymocyte proliferation activity additionally possessed an inhibitory activity for the growth of fibroblasts. These results suggest that AMoL cells may participate in the progress of the disease (leukemia), by secreting these cytokines.