Proliferating cell nuclear antigen in archival surgical specimens of malignant lymphoma and metastatic carcinoma: immunohistochemical and flow cytometric analysis.

Immunohistochemical and flow cytometric multiparameter analysis of proliferating cell nuclear antigen (PCNA) was performed on fifteen formalin fixed, paraffin embedded lymph nodes with malignant lymphoma (eleven non-Hodgkin's lymphomas, four Hodgkin's lymphomas), and fifteen lymph nodes with metastatic carcinomas. A general concordance between PCNA measurement by both methods has been observed: the percentage of positively stained cells in tissue sections correlated well with the percentage of cells expressing this antigen in cell suspensions (r = 0.76). Both diploid and aneuploid tumors expressed PCNA, and a correlation between PCNA and the percent cells in S-phase was evident in both: in PCNA-positive tumors the mean percent of cells in S-phase was 16.5%, and in PCNA-negative tumors, 5.9%. The data indicate that PCNA can be detected in formalin-fixed tissues by either classic immunohistochemical analysis or by flow cytometry.