EXPRESSION OF INTERFERON-ALPHA AND INTERFERON-GAMMA IN TESTICULAR INTERSTITIAL-TISSUE AND SPERMATOGONIA OF THE RAT

The testis is divided into two compartments: the seminiferous tubules and the interstitial tissue. The latter essentially consists of the bl ood and lymphatic vessels, testosterone-producing Leydig cells, and te sticular macrophages. In the exploration of the testicular antiviral d efense system, we initially searched for interferon (IFN) production b y the seminiferous tubule cells. The site of virus entry into the test is is probably the interstitial compartment; thus, it is important to know whether and how the cells in this compartment are protected again st viral infection. In addition, as germ cell precursors (spermatogoni a) are only partially protected by the blood-testis barrier, it was im portant to explore the antiviral capability of these cells. In this st udy we searched for IFN production by Leydig cells, testicular macroph ages, and spermatogonia after exposure to Sendai virus. We also invest igated the effect of viral exposure on testosterone production by Leyd ig cells. Our results show that spermatogonia do not constitutively ex press IFNs and give a very poor response to the virus. In contrast, te sticular macrophages constitutively produced type I IFNs, and this pro duction was markedly stimulated by Sendai virus. Leydig cells produced twice as much type I IFNs as testicular macrophages after viral expos ure, and they were the only cells producing both IFN alpha and -gamma, with these IFNs being dramatically induced/increased in response to e xposure to the virus. Furthermore, incubation of Leydig cells with the Sendai virus stimulated testosterone production. In conclusion, this study further establishes the topography of IFN expression within the testis. This allows us to hypothesize that the potential antiviral sys tem represented by Leydig cells and, to a lesser extent, by macrophage s plays a key role in protecting both androgen production and spermato genesis.