Opposing effects of sol-IgM and imm-IgM on PARP cleavage and Mcl-1 expression. (A) CLL B cells were stimulated for 40 hours with sol-IgM (10 μg/mL), sol-F(ab′)2 fragments (5 μg/mL), or imm-IgM (10 μg/mL). Protein extracts were analyzed by immunoblotting with antibodies against PARP, Mcl-1, Bcl-2, and β-actin. Two representative cases are shown. (B) Summary of changes in Mcl-1 (dark bars) and Bcl-2 (light bars) protein levels after 40-hour stimulation of CLL B cells with sol- and imm-IgM. For quantification, band intensities were first normalized to the respective actin signal and then calculated as fold change relative to unstimulated CLL B cells, which was set to 1.0. Values represent mean of 10 different cases (5 M-CLL, 5 U-CLL); error bars indicate SEM. Med indicates medium.
