BCR triggering modulates surface expression of adhesion molecules and chemokine receptors, which is abrogated by R406. (A) Overlay histograms that depict relative fluorescence intensities of CLL cells from a representative patient, stained with fluorescence-labeled mAbs to the antigens displayed on the horizontal axes. CLL cells were cultured in medium (control) or in medium supplemented with anti-IgM. The solid gray histogram represents the staining of anti-IgM–treated CLL cells, whereas the black line represents the staining of control CLL cells. The numbers next to each of the histograms indicate the mean fluorescence intensity values for the anti-IgM–stimulated samples (in gray) or the controls (in black). Compared with the controls, anti-IgM induces up-regulation of CD40, CD44, CD54, and CD62L, and down-regulation of CXCR4. (B) Displayed are bar diagrams that depict the mean relative changes in surface molecule expression on CLL cells after stimulation with anti-IgM. Results were displayed as percentage of change in expression, relative to the control samples, based upon the mean fluorescence intensity ratios (MFIR) for each of the mAbs displayed on the horizontal axis. Each bar represents the mean (± SEM) from 15 different CLL patient samples, and each of the displayed changes was statistically significant, with P < .05. (C) R406 abrogates anti-IgM–induced changes in expression of surface molecules. The bars represent the mean (± SEM) relative expression of the antigens displayed on the horizontal axis, on CLL cells from 6 different patients. ▩ depicts the mean relative surface expression after 24 hours of stimulation with anti-IgM, whereas ■ represents the mean relative surface expression after 24 hours of stimulation with anti-IgM plus R406. The expression was normalized for each antigen to the relative antigen expression on control CLL cells from the respective patient, cultured in medium alone (100%).