Presence of the bcl-2 protein and apoptosis in non-Hodgkin lymphomas with diffuse growth pattern

In an attempt to further clarify the role of the apoptosis-counteracting protein bcl-2, non-Hodgkin lymphomas (NHL, n = 170) were examined immunohistochemically, across the boundaries of histologic classification, for the presence of this oncoprotein, in comparison with apoptotic indices (A1) and percentages of Ki-67⁺ cells (growth fraction). The results of this retrospective study revealed a highly significant inverse relationship ('mirror image') between the proportion of bcl-2⁺ cells and the A1 per case. Both these parameters, although variable, clearly distinguished low- from high-grade-malignancy lymphomas according to the Kiel classification. Cluster analysis detected 2 separate groups of high-grade NHL, one with rather high A1 and low percentages of bcl-2⁺ cells, comprising most anaplastic large-cell lymphomas, the other group with reverse characteristics. We found no correlation between the percentage of bcl-2⁺ cells per case and overall survival.