Induction of ornithine decarboxylase in the liver and spleen of mice by interleukin 1-like factors produced from a macrophage cell line

Abstract

Injection of culture medium of P388D1 cells, a murine macrophage cell line, into mice produced a rapid induction of ornithine decarboxylase in the liver and spleen. The ornithine decarboxylase-inducing factor in the medium was purified by gel-filtration and chromatofocusing. With these procedures, the factor was usually found in the fraction of interleukin 1 (a lymphocyte-activating factor), indicating that the factor is identical with interleukin 1 or a molecule closely related to interleukin 1. The ornithine decarboxylase induction by the factor was suppressed by cycloheximide, but actinomycin D did not suppress the induction, or rather enhanced it. These findings may provide valuable information on the important roles of macrophages in immune responses or in inflammatory reactions.