Leukemia inhibitory factor production by rat mast cells

Leukemia inhibitory factor (LIF) is a pluripotent cytokine of importance in the regulation of immune and inflammatory responses. This cytokine may play an important role in neuronal development and bone metabolism. We have examined the ability of freshly isolated rat mast cells and mast cell lines to produce LIF at both the mRNA and bioactivity levels. Initial experiments demonstrated that two mucosal mast cell‐like cell lines RBL.2H3 and RCMC9 endogenously produced low levels of LIF bioactivity. The production of this cytokine was examined using a hepatocyte‐stimulating factor activity assay and confirmed by the use of neutralizing antibodies specific for LIF. This production was enhanced by treatment with the calcium ionophore A23187. No interleukin‐6 production was observed by these cells either endogenously or following ionophore activation. Freshly isolated highly purified rat peritoneal mast cells also expressed mRNA for LIF. These results could have important implications for the role of mast cells in neuronal development, hematopoiesis bone metabolism and the acute‐phase response.