Fig. 2.

EVI5: relative RNA levels in lymphomas from BCL6 transgenic and control mice and immunohistochemistry of BCL6-positive and -negative murine and human lymphomas. (a) The graph depicts average relative EVI5 RNA expression from the lymphomas (all T-cell) of three retroviral-injected BCL6 transgenic mice (black bar) containing inserts within the terminal intron or 3′-untranslated region of the EVI5 gene as compared with three randomly selected T-cell lymphomas from retroviral-injected non-transgenic controls that did not contain inserts in or near EVI5 (gray bar). Expression in each transgenic animal was decreased as compared with the controls [range, 1.3 to 2-fold (Table 1), overall decrease, 1.86-fold; mean ± SEM = 0.007 ± 0.001 in the controls as compared with 0.004 ± 0.0007 in the transgenics; P < 0.05]. (b) I, Representative murine lymphomas from (1) a transgenic mouse (nuclei positive for BCL6, column B) and (2) a non-transgenic mouse (nuclei negative for BCL6). The nuclear staining evident in the anti-BCL6 (C) column is decreased in the transgenic mouse as compared with the non-transgenic control. II, Representative human lymphomas: (1) BCL6-positive B-cell, (2) BCL6-positive (T-cell), (3) BCL-negative (B-cell), (4) BCL-negative (T-cell); the cytoplasm of the tumor cells stains strongly positive with the T-cell marker CD3 (II, 4A). A germinal center in 4A (upper left corner) does not stain with CD3 and is BCL6-positive (column B), whereas the tumor cells around it are BCL-negative. As in the murine lymphomas, the EVI5 nuclear staining (column C) is decreased in BCL6-positive cells (tumors 1 and 2, or germinal center cells, tumor 4) as compared with the stronger expression in the BCL-negative tumor cells [tumors 3 and 4 (outside the germinal center)]. The length of the bar in the lowest right panel depicts 50 μm.