Production of interleukin-5 by mouse astrocytes and microglia in culture.

Interleukin (IL)-5 was originally isolated as a B cell growth factor derived from T cells and is known as a multipotent cytokine. We found that IL-5 was detected in the cultures of microglia and astrocytes by both the enzyme-linked immunosolvent assay (ELISA) and bioassay with IL-5-dependent cell line, T88M. We also found that microglia and astrocytes expressed IL-5 mRNA. IL-5 receptor mRNA, however, was not detected in these cells. Stimulation with interferon-gamma increased expression of IL-5 in astrocytes and microglia. These results suggest that IL-5 produced by brain cells may be involved in the interaction between brain cells and immune cells in the brain.