Sertoli cells induce xenolymphocyte apoptosis in vitro

Testicular Sertoli cells can protect pancreatic islet grafts from allo- and autoimmune destruction; however, the mechanisms underlying immune privilege of the testicle are not well understood, especially in xenotransplantation. The purpose of this study was to investigate whether rat Sertoli cells could induce mouse lymphocyte apoptosis in vitro.

Testis was isolated from 2- to 4-week-old Sprague Dawley (SD) rats. Sertoli cells were successfully prepared by digestion with collagenase type V, trypsin, and DNase I, and then identified by electron microscope. Viability and apoptosis of cultured cells were measured by flow cytometry. We examined the apoptosis rates of Balb/c mouse lymphocytes, which were cocultured with SD rat Sertoli cells by FACS. The expression of Fas ligand (Fasl), transforming growth factor (TGF)-beta1 and clusterin on Sertoli cells were detected by immunocytochemistry.

In the cocultured system, Sertoli cells accounted for more than 93%. With our isolation method, the viability of Sertoli cells was more than 95% and the apoptosis rate was 10.87% +/- 3.87%. The lymphocyte apoptosis ratio was 15.52 +/- 0.17 (P < .01, compared with the control groups). SABC immunochemistry staining showed that the sertoli cells could express FasL, TGF-beta, and clusterin.

In our coculture in vitro, rat Sertoli cells expressed FasL and TGF-beta1 as well as induced the apoptosis of mouse lymphocytes. These results indicated that the expression of FasL and TGF-beta1 on Sertoli cells might relate to immune privilege in xenotransplantation.