EXPRESSION OF AMINOPEPTIDASE-N (CD-13) IN NORMAL-TISSUES AND MALIGNANT NEOPLASMS OF EPITHELIAL AND LYMPHOID ORIGIN

Aims-To provide a detailed knowledge of the distribution of the CD13 m olecule, also known as the protease aminopeptidase-N, on both normal t issues and malignant neoplasms of epithelial and lymphoid origin. Meth ods-CD13 antigen was examined by immunocytochemistry, using a recently produced antibody (VS5E) alongside a commercially available anti-CD13 monoclonal antibody. The VS5E recognising CD13 was produced by immuni sing a doxorubicin resistant breast cancer cell line (MCF-7-Adr). A st riking feature of this antibody was that it stained the doxorubicin re sistant cells but not the parental cell line. Both antibodies were tes ted on a broad range of normal tissues and three common types of epith elial malignancy (colon n = 28, lung n = 30, breast n = 35), and 12 ca ses of Hodgkin's and 52 of non-Hodgkin's lymphomas. Results-CD13 was e xpressed on many tissue and cell types outside the haematopoietic syst em. In particular it was present on breast epithelium and in 20% (seve n of 35) of breast carcinomas, but absent in normal and neoplastic col onic and bronchial tissues and lymphomas. Conclusions-This study provi des not only detailed information about the expression of the CD13 ant igen, but also raises the important possibility that CD13 expression m any correlate with drug resistance in breast carcinomas.