BCL-2 AND BAR PROTEIN EXPRESSION IN INDOLENT VERSUS AGGRESSIVE B-CELLNON-HODGKINS-LYMPHOMAS

Bcl-2 and bar are cellular proteins that are important in the regulati on of apoptosis. Overexpression of bcl-2 protein is associated with pr olonged cell survival, whereas overexpression of bar correlates with i ncreased apoptosis after injury. It has been suggested that the ratio of bcl-2 and bar deter-mines a cell's susceptibility to apoptosis. We studied bcl-2 and bax expression by immunohistochemical methods in 46 cases of B-cell non-Hodgkin's lymphoma characterized by the Revised Eu ropean;American Lymphoma (REAL) classification to determine whether ex pression of these two proteins correlated with the histological subtyp e or the predicted clinical behavior (indolent v aggressive). For each case, both the percentage of cells staining as well as the intensity of staining of bcl-2 and bar were recorded, and a bcl-2-bax protein ra tio (BBPR) was calculated. Baa; staining was identified in 100% of the lymphomas studied. In contrast, bcl-2 staining was seen in only 67%. Bcl-2 expression correlated with the subtype of lymphoma with positive staining in 100% of small lymphocytic lymphomas, 80% of follicle cent er lymphomas, 38% of diffuse large cell lymphomas, 33% of high-grade B -cell Burkitt's-like lymphomas, 0% of Burkitt's lymphomas, and 0% of B -cell lymphoblastic lymphomas. The BBPR of indolent lymphomas (mean, 1 .8) was significantly greater than the BBPR of aggressive lymphomas (m ean, 0.6) (P less than or equal to .002). This suggests that bar and b cl-2 expression may be linked to biological behavior in non-Hodgkin's B-cell lymphomas. Copyright (C) 1998 by W.B. Saunders Company.