Correlations between apoptotic and proliferative indices in malignant non-Hodgkin's lymphomas

Cell production versus cell loss rates were estimated, across the boundaries of histological classification, in 50 cases of malignant non-Hodgkin's lymphomas by use of mitotic indices, percentage of Ki-67+ cells and percentage of PC10+ cells as proliferative indices, and the relative number of apoptotic bodies (apoptotic indices, AIs) as parameters. Regression analysis revealed significant (P < 0.01) positive correlations between the AIs and the proliferative indices; among the immunohistochemically assessed proliferative indices; and between these, the mitotic indices and the AIs on the one hand and histological malignancy grades on the other hand. The cellular protein BCL-2, which counteracts apoptosis, was significantly (P < 0.01) more often expressed in lymphomas with low than in those with high AIs. Multivariate analysis of data showed that of all parameters tested in this series, only the AIs correlated significantly (P < 0.05) with overall lethality. The correlation between BCL-2 positivity of lymphoma cells and overall survival did not quite attain significance (P = 0.08). Results of the present study suggest that high AIs and lack of BCL-2 expression may be adverse prognostic factors, independent of histological grade.