Flow cytometric analysis of DNA content and keratins by using CK7, CK8, CK18, CK19, and KL1 monoclonal antibodies in benign and malignant human breast tumors

Abstract

We have used a double‐labelling flow cytometry analysis of keratin (CK) and DNA in breast cancer. Five monoclonal anti‐keratin antibodies were tested: KL1 recognizing M_r 55,000–57,000 keratins, and “anti‐glandular epithelia,” LE41, RGE‐53, and LP2K specific for CK n° 7, 8, 18, and 19 of Moll's classification, respectively. Flow cytometric (DNA‐CK) analysis was performed on 10 benign and 19 malignant human breast tumors. All the benign tumors were diploid and 63% of the malignant tumors were aneuploid. This technique permits the analysis of DNA in the epithelial fraction alone. In aneuploid tumors, gating the DNA‐keratin‐positive population allowed accurate DNA analysis without interference due to debris background and non‐epithelial cells. Moreover, double‐labelling using the CK19 antibody gave a better identification of near‐diploid tumors. An enhancement of keratin expression in malignant tumors was observed with CK 19 (P < 0.001), KL1 (P < 0.01), CK 8 (P < 0.05), and CK18 (n.s.) compared to benign tumors. The comparison of keratin expression in aneuploid and diploid malignant tumors revealed reduced CK8, CK18, and CK19 in the former.