LEUKEMIA INHIBITORY FACTOR MESSENGER-RNA IS EXPRESSED IN CORTICAL ASTROCYTE CULTURES BUT NOT IN AN IMMORTALIZED MICROGLIAL CELL-LINE

Leukemia inhibitory factor (LIF) is a multifunctional cytokine synthes ized by a variety of cell types. In the nervous system LIF affects neu ronal differentiation, and may be important during cerebral infection and inflammation. To clarify the cellular source of LIF in the brain, we examined the expression of LIF mRNA by primary cortical astrocyte c ultures and an immortalized microglial cell line. The microglial cell line did not express LIF mRNA in response to pro-inflammatory agents s uch as lipopolysaccharide (LPS) that induced expression of other cytok ine mRNAs. In contrast, primary astrocyte cultures grown in serum-cont aining medium expressed LIF mRNA constitutively, and this expression w as regulated by pro-inflammatory and anti-inflammatory stimuli. Agents which activate the cAMP and protein kinase C second messenger systems also increased LIF mRNA in astrocyte cultures. These results suggest that astrocytes, but not microglia, may be an important source of LIF during cerebral inflammation and infection.