Monocyte chemotactic protein-1 expression in human preovulatory follicles and ovarian cells

There is a considerable population of macrophages (5-15% of the cells) within the human ovarian follicle at the time of ovulation. Macrophages are also present within the ovarian stroma, mostly near perifollicular capillaries. We hypothesized that macrophage migration in and around the preovulatory follicle is hormonally regulated and that regulation of macrophage migration occurs through local modulation of monocyte chemotactic protein-1 (MCP-1) that chemoattracts and activates monocytes/macrophages. In this regard, we investigated the expression and regulation of MCP-1 in human follicular fluid and in ovarian stromal and granulosa-lutein cell cultures. The concentration of MCP-1 in follicular fluid samples obtained from women prior to the administration of hCG was (n = 4) 90 ± 27 (mean ± S.E.) pg/ml; in samples obtained 12 h after the hCG administration it was (n = 3) 135 ± 23 pg/mL; in follicular fluids obtained 34 h after the hCG administration it was (n = 126) 322 ± 46 pg/mL (P = 0.007 vs. pre-hCG). The mean ratio of follicular fluid/serum MCP-1 levels was 4.18. There was a correlation between follicular fluid MCP-1 levels and follicular fluid or serum progesterone levels (r = 0.21, P = 0.02; r = 0.29, P = 0.03, respectively). MCP-1 mRNA and the protein were expressed in ovarian stromal and granulosa-lutein cells in culture and were increased by interleukin-1α and tumor necrosis factor-α in a time- and concentration-dependent manner. LH/hCG induced higher levels of MCP-1 mRNA expression and protein production in both cell cultures. We propose that regulation of MCP-1 in ovarian stromal and granulosa-lutein cells by cytokines may play a role in the physiology of periovulatory events.