Detection and localization of placental protein 14-like protein in human seminal plasma and in the male genital tract.

The concentration of PP14 in seminal plasma was determined by radioimmunoassay. The levels were 13-362 mg/liter in normospermic specimens (n = 36), 10-252 mg/liter in samples from 46 infertile men (oligo-, astheno-, terato- or necrospermia), and 30-233 mg/liter in 7 vasectomized men. No significant difference was found in the PP14 levels in the groups examined. Low PP14 levels (13-25 micrograms/liter) were detected in male sera. In RIA, serial dilutions of seminal plasma and purified PP14 gave parallel dose-response curves. In tandem-crossed immunoelectrophoresis, seminal plasma PP14 showed a reaction of identity with PP14 purified from human term placenta. The isoelectric point of seminal plasma PP14 was 5.2-5.4 and that of early maternal serum PP14 was 4.8-4.9. In the normospermic group a moderate negative correlation (p less than 0.05) was found between the volume of seminal plasma and the PP14 level, whereas the correlation was positive (p less than 0.05) in the infertile group. There also was a negative correlation (p less than 0.05) between the percentage of motile spermatozoa and PP14 concentration. No correlation was observed between the sperm count or age of men and PP14 level in seminal plasma. The origin of seminal plasma PP14 is not from the testes, as the levels in vasectomized and nonvasectomized men were similar. By immunoperoxidase staining, PP14 was detected in the epithelium of seminal vesicles but not in the testis.