MITOGENIC EFFECTS OF INTERLEUKIN-5 ON MICROGLIA

Interleukin-3 (IL-3), interleukin-5 (IL-5), and granulocyte macrophage -colony stimulating factor (GM-CSF) are cytokines that bind to recepto r complexes comprised of unique a-receptor subunits specific for each ligand and a commonly shared B-receptor subunit. Previous studies have shown that IL-3 and GM-CSF induce mitosis in microglia and macrophage cells, indicating the functional presence of their cognate receptors. In this study, it is shown that the third member of this cytokine gro up, IL5, also serves as a microglia mitogen. Proliferative effects wer e seen in culture on both murine microglia and a murine macrophage cel l line, RAW 264.7. Since IL-5 is known to be secreted by both microgli a and astrocytes in response to inflammatory stimuli, these results in dicate that IL-5 may be involved in the cytokine-immune cascades leadi ng to microglia proliferation in areas affected by disease and tissue damage.