Inhibin and activin are demonstrable by immunohistochemistry in ovarian tumor tissue.

Elevated serum immunoreactive inhibin concentrations have been reported in patients with mucinous and granulosa cell tumors of the ovary. The present study aimed to determine whether the inhibins and/or the related peptides, the activins, were demonstrable within ovarian tumor tissue. Immunohistochemical analyses were performed on 11 ovarian tumors, 5 mucinous, 3 serous, 1 granulosa, 1 clear cell, and 1 metastatic colonic cancer. Both monoclonal and polyclonal antisera specific for inhibin-A, activin-A, and activin-B, and their alpha-, beta A- and beta B-subunits were used. The mucinous cells of all five mucinous tumors showed positive staining for activin-A and activin-B, and their beta A- and beta B-subunits, and three stained positive for inhibin-A and the alpha-subunit. The granulosa cell tumor also showed positive staining for inhibin-A and the activins. The remaining tumors were negative. The findings are consistent with the hypersecretion of inhibin (and possibly activin) by some ovarian malignancies and suggest that immunohistochemistry for the inhibins and the activins should be explored further in the classification of ovarian malignancies.