EFFECTS OF INTERLEUKIN-6, INTERLEUKIN-2, AND TUMOR-NECROSIS-FACTOR-ALPHA ON TRANSFERRIN RELEASE FROM SERTOLI CELLS IN CULTURE

Recent studies demonstrate that several cytokines are potent modulators of steroid release from the testis. In an attempt to determine whether these agents may influence other types of secreted substances, we used plaque assays to measure the effect of interleukin-6 (IL-6), interleukin-2 (IL-2), and tumor necrosis factor alpha on transferrin (TF) release from Sertoli cells in culture. Because Sertoli cells from different parts of the tubule respond differently to modulatory factors, we used cultures obtained by microdissection from stages III-V, VII, IX-XI, and XIII of the cycle of the seminiferous epithelium. Our results revealed that each agent increased the rate of TF plaque formation from cultures of IX-XI, and XIII staged segments but not from those staged III-V and VII. Moreover, IL-6, but not the other cytokines, modified the response of Sertoli cells to another regulator, FSH. This was evidenced by our findings that pretreatment with IL-6 for 1 h resulted in FSH-induced increases in the rate of plaque formation for cells from IX-XI segments, in addition to those segments which are normally responsive without pretreatment (III-V and VII segments). Further experiments revealed that IL-6 also had a chronic influence on the proportions of TF secretors present in certain staged cultures. Treatment for 24 h with IL-6 markedly reduced the percentage of TF secretors in cultures from stage XIII segments and resulted in a slight increase in TF cells for stage VII cultures. However, no chronic influences in TF secretors were detected with either IL-2 or tumor necrosis factor alpha treatment. Our results demonstrate very clearly that certain cytokines acting in a stage-specific manner have acute and/or chronic influences on the release of TF from Sertoli cells. These findings, when viewed in light of reports of the presence of these factors in the testis, suggest strongly that cytokines or cytokine-like substances, by modulating the release of Sertoli cell substances, may play an important role in testis function.