Astrocytes of the brain synthesize interleukin 3-like factors.

Interleukin 3 (IL 3) is produced by T lymphocytes and T cell lines, as well as by a myelomonocytic cell line (WEHI-3), and it activates lymphocytes and mast cells, as well as macrophages. Recently we have demonstrated that astrocytes act as immune accessory cells through the secretion of interleukin 1 and the presentation of antigens to T lymphocytes. Here we show that cultured astrocytes from newborn mice release a 30,000 m.w. factor that induces the expression of 20-alpha-hydroxysteroid dehydrogenase in nu/nu spleen cells and the proliferation of the IL 3-dependent cell line 32DCL. An analogous biological activity was detected in supernatant of cultured rat C6 glioma cells. Production of IL 3-like factors by astrocytes of the central nervous system may be essential for development and maintenance of hemo and lymphopoietic cells within inflammatory brain lesions.