Cell turnover parameters in small and large cell varieties of primary intestinal non‐hodgkin's lymphoma

BACKGROUND In contrast to primary gastric lymphoma, primary intestinal lymphoma is an uncommon condition with a poorer outcome, perhaps due to differences in its pathogenesis. In this study, the authors analyzed the roles of proliferation and apoptosis in the pathogenesis of intestinal lymphoma. METHODS Fifty‐one cases of intestinal non‐Hodgkin's lymphoma (NHL) (10 small B‐cell mucosa‐associated lymphoid tissue [MALT] NHLs, 12 large B‐cell MALT NHLs, 18 large B‐cell NHLs, 2 small T‐cell NHLs, 7 large T‐cell NHLs, and 2 mantle cell NHLs) were studied for the immunohistochemical expression of MIB‐1 and the TUNEL assay as well as the expresssion of bcl‐2 and p53, both of which are regulatory gene products involved in apoptosis. RESULTS The median proliferation index (PI) was 37.3%, and the median apoptotic index (AI) was 1.10%. The respective values of PI and AI were 5.8% and 0.06% in small B‐cell MALT lymphoma, 52.8% and 0.24% in large B‐cell MALT lymphoma, 58.85% and 1.36% in large B‐cell lymphoma, 30.9% and 1.93% in mantle cell lymphoma, 18.13% and 1.25% in small T‐cell lymphoma, and 43.4% and 1.93% in large T‐cell lymphoma. In an analysis of B‐cell NHL only (with mantle cell NHL excluded), proliferative and apoptotic indices were positively correlated (correlation coefficient = 0.563, P < 0.001). Furthermore, high bcl‐2 expression was inversely correlated with both PI and AI. Expression of p53 was observed in 8 cases (1 small cell lymphoma and 7 large cell lymphomas). CONCLUSIONS Small cell lymphomas had low AI and PI values, whereas large cell lymphomas had high AI and PI values. Apoptosis and proliferation were positively correlated, and higher expression of bcl‐2 was associated with lower rates of apoptosis. Cancer 1998;83:158‐165. © 1998 American Cancer Society. An analysis of the role of proliferation and apoptosis in primary intestinal non‐Hodgkin's lymphoma demonstrated that these cell turnover parameters are different in small and large cell varieties of the disease.