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Monoclonal antibodies (MAb) C219 and JSB-1 have been used extensively in the analysis of P-glycoprotein expression in normal and malignant tissues. This study demonstrates that some commercial lots of these MAb, even those supplied as purified immunoglobulins, contain contaminating anti-A blood group antibodies. In both sources of reagent, the antibody was specific for a particular A structure, known as repetitive or Type 3 A. These observations may account for earlier studies showing polymorphic variation in P-glycoprotein expression in epithelial tissues and an apparent correlation with the A blood type of the donor. Such reactivity can be eliminated by absorption of anti-P-glycoprotein reagents with A erythrocytes. These data re-emphasize the importance of evaluating MAb samples for unsuspected contaminating antibodies.

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.

The immunoanatomy of the human kidney and urinary tract has been analyzed by a panel of mouse anti-human monoclonal antibodies that define specific domains and structures. The differentiation antigens detected by these monoclonal antibodies represent a series of glycoproteins characteristic of different cell types. They differ from the blood group antigens and appear to be distinct from other antigens previously described within the kidney or urinary tract. The antigens recognized by these monoclonal antibodies represent an immunohistologic dissection of the human nephron. These antibodies have a broad range of potential applications in studying embryogenesis and pathogenesis of nonneoplastic and neoplastic diseases of the human kidney and urothelium.