To delineate the scope of the human intraovarian IL-1 system we used a solution hybridization/RNase protection assay to test for expression of the genes encoding IL-1, its type I receptor (IL-1R), and its receptor antagonist (IL-1RA). IL-1 transcripts were not detected in whole ovarian material from days 4 or 12 of an unstimulated menstrual cycle but transcripts (IL-1β ≫ IL-11α) were detected in preovulatory follicular aspirates from gonadotropin-stimulated cycles. Concurrently obtained peripheral monocytes did not contain IL-1β transcripts but macrophage-depleted follicular aspirates did, thus implicating the granulosa cells as the site of IL-1 expression. IL-1R transcripts were detected in RNA from whole ovaries and follicular aspirates but not in RNA from peripheral monocytes. IL-1 RA transcripts were detected in whole ovarian material as well as in macrophage-free follicular aspirates. Cultured human granulosa and theca cells did not contain mRNA for IL-1β or IL-1RA but did contain mRNA for IL-1R. Treatment of cell cultures with forskolin (25 μM) induced IL-1β transcripts in granulosa but not theca cells. Forskolin also increased the basal levels of IL-1R transcripts in both granulosa and theca cells but did not induce IL-RA transcripts in either cell type. Taken together, these findings reveal the existence of a complete, highly compartmentalized, hormonally dependent intraovarian IL-1 system replete with ligands, receptor, and receptor antagonist.
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