Secretory leukocyte protease inhibitor (SLPI) concentrations in cervical mucus of women with normal menstrual cycle

Secretory leukocyte protease inhibitor (SLPI) is a potent inhibitor of huma n leukocyte elastase, SLPI transcripts in the cervical tissue were detected during the menstrual cycle by reverse transcription-polymerase chain react ion (RT-PCR). Western blot analysis revealed that the intensity of SLPI pro tein in cervical tissue in the ovulatory phase was stronger than in other p hases. Immunohistochemistry using an anti-SLPI polyclonal antibody revealed positive staining in the epithelial cells of the endocervix. Western blot analysis also revealed that SLPI protein was present in the cervical mucus. Again the intensity of SLPI protein in the ovulatory phase was stronger th an that in the follicular phase. The SLPI concentrations and SLPI/elastase ratios in the cervical mucus of women in the ovulatory phase were significa ntly higher than in the follicular and luteal phases. The SLPI and elastase concentrations in the cervical mucus were positively correlated, No signif icant difference was found in the SLPI serum concentrations of women during the menstrual cycle. These results suggest that production of SLPI from ce rvical epithelial cells during the ovulatory phase may be important for pro tection from the effects of elastase.