Immunohistochemical localization of P-glycoprotein in adult human ovary and female genital tract of patients with benign gynecological conditions.

The multidrug-resistance gene, MDR1, encodes a plasma membrane glycoprotein termed P-glycoprotein, which mediates active cellular efflux of certain cytotoxic agents. Two mouse monoclonal antibodies (MAb), C219 and JSB-1, were used to identify P-glycoprotein in frozen tissue from the female genital tract of 14 women with benign gynecological conditions; multiple samples from several sites in the genital tract were available from seven patients. P-glycoprotein was detected in the ovarian surface epithelium in four of 14 cases, in the Fallopian tube in three of five cases, in occasional epithelial cells of the endometrial glands in two of five cases, in some endocervical glandular epithelium in three of five cases, in ectocervical squamous epithelium in one of the two cases, and in luteinized cells of the eight cases in which a corpus luteum was present in the specimen. Positive staining with these two MAb was also observed in some endothelial cells in the cortex of the ovary and in the stromal tissue of the myometrium, endometrium, and endocervix. These studies suggest that, if epithelial ovarian cancers are derived from the surface epithelial cells of the ovary, a small proportion of the cancers might be expected to retain the phenotype found in non-cancerous cells and to express P-glycoprotein.