Correlation between the number of apoptotic cells and expression of the apoptosis‐related antigens Fas, Le^y and bcl‐2 protein in non‐Hodgkin's lymphomas

The relationship between the number of apoptotic cells and the expression of apoptosis‐related antigens was examined In 56 cases of non‐Hodgkin's lymphomas and in 10 cases of reactive hyperplastic lymph nodes (RHL). Apoptosis was visually quantified by the in situ end‐labeling (ISEL) method, and the expression of Fas, Le^y antigens and bcl‐2 protein was examined by Immunohistochemistry. The expression of Le^y antigen was observed in germinal centers of RHL and 45% of non‐Hodgkin's lymphomas. The apoptotic cell count (AC) in follicular lymphomas was significantly less than that in diffuse lymphomas. The distribution pattern of apoptotic cells In follicular lymphomas was inverse to that in RHL. In follicular lymphomas, AC was lower in follicles than in inter‐follicular areas. In contrast, AC was higher in follicles than in Interfollicular areas in RHL. Le^y antigen‐positive lymphomas showed a significantly higher AC than the negative cases. The Fas antigen‐positive lymphomas showed a higher AC than the negative cases. However, AC in bcl‐2 protein‐positive and negative cases was not significantly different. These results suggest that Le^y and Fas antigens appear to be involved in the apoptotic tendency of tumor cells in non‐Hodgkin's lymphomas, whereas bcl‐2 does not necessarily.