Abstract

We investigated the expression of proliferating cell nuclear antigen (PCNA/cyclin) in human melanocytic tumors, using the anti-PCNA monoclonal antibody (clone PC10) and compared the results with previous findings with clone 19A2, another monoclonal antibody. The expression of PCNA in formalin-fixed and paraffin-embed-ded pathological tissues increased in accordance with the progression of tumor. In normal tissues, PCNA-positive cells were mainly in basal and suprabasal layer by PC10, whereas nuclear labeling of 19A2 was found in suprabasal layer of epidermis. The population of PCNA-positive cells in common melanocytic nevi were significantly higher than 19A2-positive cells. There were, however, no significant differences between PC10 and 19A2 in the number of cells they recognized in malignant melanomas. The antigen recognized by clone PC10 appears to be a more common epitope in PCNA/cyclin than that of 19A2. Therefore, application of other markers for cell proliferation and a careful interpretation of the results are necessary to evaluate the correlation between immunoreactivity of clone PC10 and to establish the degree of malignancy in the diagnosis of tumors of melanocytic origin.