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 men. Design: Prospective laboratory study. Setting: Urology laboratory in a university hospital. Patient(s): Men undergoing testicular biopsy during an investigation of subfertility. Intervention(s): None. Main Outcome Measure(s): Expression of the c-kit receptor protein, stem cell 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 in only Leydig cells of Sertoli cell-only specimens. Stem cell factor was demonstrated in Leydig cells and Sertoli cells in all specimens. Western blotting demonstrated the 150-kd c-kil protein in the normal testes and the testes with maturational arrest, but not in the testes with the Sertoli cell-only pattern. Stem cell factor was expressed in all specimens, with a protein size of 45 kd. Increased apoptosis was demonstrated in type A spermatogonia and spermatocytes of tissue with maturational arrest compared with normal testicular tissue. Conclusion(s): C-kit receptor expression is decreased in subfertile testicular tissue compared with normal testicular tissue. Stem cell factor expression is present in Leydig cells and Sertoli cells. Increased apoptosis is seen in tissue with maturational arrest compared with normal tissue. (C) 1998 by American Society for Reproductive Medicine.