Lipocalin-type prostaglandin D synthase in human male reproductive organs and seminal plasma.

Prostaglandin D synthase (PGDS) activity was detected in human seminal plasma (0.05-1.83 nmol/min per milligram protein). The enzyme was purified from human seminal plasma by immunoaffinity chromatography and found to be 27 kDa in size and N-glycosylated, similar to PGDS in the cerebrospinal fluid. The N-terminal amino acid sequence of 16 residues of the seminal enzyme, APEAQVSVQPNFQQDK, was identical to that of the cerebrospinal fluid PGDS. Although PGDS activity and the content determined by the immunoassay each highly varied in the seminal plasma, the concentration was significantly (p < 0.001) lower in the oligozoospermic group (2.47 +/- 0.51 microg/ml) than in the normozoospermic group (9.75 +/- 1.49 microg/ml). Prostaglandin (PG) D2 was detected in the seminal plasma (5.00 +/- 0.65 ng/ml) with a positive correlation to the PGDS concentration (p < 0.05). PGD2 was converted to the J series of PGs in the seminal plasma with a half-life of 6.5 h. Northern blot analysis revealed that mRNA for PGDS was expressed in the testis, prostate, and epididymis. Through immunohistochemistry, PGDS was localized in Leydig cells of the testis and in epithelial cells of the prostate and ductus epididymidis.