Testicular immunoregulatory factors.

The present data indicate that immune cells are regulated locally in the testis by Leydig cells, Sertoli cells and resident testicular macrophages. The effects of these cells are mediated by several peptide factors, including protectin, a group of high molecular weight testicular immunosuppressive factors, and testicular interleukin-1 alpha-like factor. The testicular interleukin-1 alpha-like factor is produced by Sertoli cells and is under hypophyseal control. Its synthesis starts at puberty concomitantly with the onset of spermatogenesis and it may act as a spermatogonial growth factor. Protectin, which is under hypophyseal control, may be involved in the mechanism of prolonged transplant survival in the testicular interstitial tissue. Its levels increase at puberty. Both the testicular interleukin-1 alpha-like activity and protectin may be important in testicular pathophysiology.