Production of interleukin-12 and expression of its receptors by murine microglia.

Production of interleukin-12 (IL-12) by cultured murine microglia and astrocytes was examined, by means of ELISA to detect heterodimeric p70 and RT-PCR to analyze the expression of mRNA encoding p35 and p40. Microglia, but not astrocytes, produced IL-12 p70 in response to lipopolysaccharide and interferon-gamma. The microglial cell line, Ra2, produced only p40, but not p35, upon above stimulation. Thus, it is possible that some population of microglia induce helper 1 type T cell response via producing IL-12 in the CNS. Microglia were induced to express mRNA encoding IL-12 receptors which were exclusively expressed in activated T and NK cells.