Interleukin-1 alpha stimulation of spermatogonial proliferation in vivo

Interleukin-1 (IL-1) is a family of hormone-like polypeptides originally isolated from cultures of activated monocyte/macrophages and known to act as a potent mediator of inflammation (Dinarello 1984). The effects of IL-1 include augmentation of T and B lymphocyte proliferation (Oppenheim and Gery 1982), but also mitogenic effects on a wide variety of other cells such as fibroblasts (Libby et al. 1985), glial cells (Giulian and Lachman 1985), keratinocytes (Ristow 1987) and chondrocytes (Söder and Madsen 1988). Recent observations indicate that an IL-1-like factor with molecular characteristics similar to the macrophage-derived IL-1 alpha (March et al. 1985) is constitutively produced by the seminiferous tubules (Khan et al. 1987). The present data show that recombinant IL-1 alpha (rIL-1 alpha) stimulates DNA synthesis in intermediate and type B spermatogonia in vivo and suggest that IL-1 alpha may act as a growth factor for spermatogonia.