Mast cells in human testicular biopsies from patients with mixed atrophy: increased numbers, heterogeneity, and expression of cyclooxygenase 2 and prostaglandin D2 synthase.

OBJECTIVE: To determine intratesticular abundance and distribution of tryptase-positive mast cells (MCs) and to examine the expression of key enzymes of prostaglandin (PG) synthesis, cyclooxygenase 2 (COX2), and PGD2 synthase in the testes of men with mixed atrophy (MA) syndrome and in normal samples.
DESIGN: Retrospective study.
SETTING: Academic research institute and andrology practice. PATIENT(S): Nineteen men. INTERVENTION(S): Testicular biopsies. MAIN OUTCOME MEASURE(S): Immunohistochemistry and evaluation of COX2 and tryptase-positive MCs, laser microdissection of immunoreactive cells followed by reverse transcriptase polymerase chain reaction for COX2 and PGDS-H mRNA, and transmission electron microscopy. RESULT(S): In line with previous studies, few tryptase-positive MCs, but no COX2-positive cells, were observed in testes with normal spermatogenesis. In MA samples, the number of tryptase-positive MCs was significantly increased and the cells accumulated in the walls of the seminiferous tubules. In 11 of 13 MA samples, COX2 protein was detected. In 2 cases, Leydig cells were positive; however, in all 11 of 13 cases, COX2 was localized to MCs, coexpressing tryptase. The proportion of MCs coexpressing COX2 varied from 4% to 35%. Laser microdissection of tryptase/COX2-positive MCs followed by reverse transcriptase polymerase chain reaction revealed PGDS-H mRNA. Transmission electron microscopy identified typical MCs with abundant granules and another subtype with only a few granules, implying that MCs may differentiate in the testes. CONCLUSION(S): In patients with MA, testicular MC numbers and phenotypes change with respect to the ability to express COX2 and synthesize PGs. MCs and PGs have emerged as players in spermatogenic dysfunction.