Decreased expression of the c-kit receptor is associated with increased apoptosis in subfertile human testes

Objective: To examine the expression of the c-kit receptor and its ligand, stem cell factor, and their possible relation with apoptosis in infertile m en. Design: Prospective laboratory study. Setting: Urology laboratory in a university hospital. Patient(s): Men undergoing testicular biopsy during an investigation of sub fertility. Intervention(s): None. Main Outcome Measure(s): Expression of the c-kit receptor protein, stem cel l factor, and apoptosis in the testes. Result(s): The c-kit receptor was strongly present in Leydig cells and type A spermatogonia of normal testes, with decreased staining in Leydig cells and type A spermatogonia of testes with maturational arrest, and staining i n only Leydig cells of Sertoli cell-only specimens. Stem cell factor was de monstrated in Leydig cells and Sertoli cells in all specimens. Western blot ting demonstrated the 150-kd c-kil protein in the normal testes and the tes tes with maturational arrest, but not in the testes with the Sertoli cell-o nly pattern. Stem cell factor was expressed in all specimens, with a protei n size of 45 kd. Increased apoptosis was demonstrated in type A spermatogon ia and spermatocytes of tissue with maturational arrest compared with norma l testicular tissue. Conclusion(s): C-kit receptor expression is decreased in subfertile testicu lar tissue compared with normal testicular tissue. Stem cell factor express ion is present in Leydig cells and Sertoli cells. Increased apoptosis is se en in tissue with maturational arrest compared with normal tissue. (C) 1998 by American Society for Reproductive Medicine.