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 expression 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.