Human testicular mast cells contain tryptase: increased mast cell number and altered distribution in the testes of infertile men.

OBJECTIVE: To determine whether human testicular mast cells contain the potent fibroblast growth factor tryptase and to examine changes in mast cell morphology and intratesticular distribution in testes with normal spermatogenesis versus abnormal spermatogenesis.
DESIGN: Retrospective evaluation of testicular biopsies with the use of immunohistochemistry, morphometry, and electron microscopy.
SETTING: University research and clinical institutes. PATIENT(S): Infertile men (total of 24) with severe hypospermatogenesis, germ cell arrest syndrome, or Sertoli cell only syndrome, and men without pathologies. INTERVENTION(S): Diagnostic testicular biopsy. MAIN OUTCOME MEASURE(S): Location, number, and distribution of testicular mast cells. RESULT(S): All groups showed tryptase-positive mast cells. In specimens with normal spermatogenesis, mast cells were round and located mainly in the interstitial spaces close to Leydig cells. In germ cell arrest syndrome, a 2-fold increase was evident, and in Sertoli cell only syndrome, a >3-fold increase of tryptase-immunoreactive mast cells became evident. Moreover, there was a statistically significant shift of the cells from the interstitium to the tubular walls in Sertoli cell only syndrome and germ cell arrest syndrome. Mast cells in specimens of Sertoli cell only syndrome and germ cell arrest syndrome were heterogeneous, with rounded or elongated shapes and signs of degranulation. The thickness of the tubular walls was doubled in specimens of germ cell arrest syndrome and Sertoli cell only syndrome in comparison with normal specimens, and this increase was positively correlated with the number of mast cells in these patients. CONCLUSION(S): Our results suggest that mast cell products, including the potent fibroblast growth factor tryptase, are involved in the thickening of the tubular wall and other changes in infertile testes.