CLL cells express a low level of total CD79b protein. (A-B) Total IgM, (A,C) CD79a, and (A,D) CD79b protein in human normal naive B-cell samples (n = 10) and CLL cell samples (n = 25) were examined by immunoblot. Membranes were stripped and reprobed with anti-actin antibody as a loading control. The results in (A) show 1 representative case, and l-exp represents a longer exposure. The results in (B-D) represent relative expression of total IgM, CD79a, and CD79b protein in CLL samples (lines represent mean ± standard error of the mean [SEM] of 25 samples), with total IgM, CD79a, and CD79b protein expression in human normal naïve B-cell samples set at “1.0” (lines represent mean ± SEM of 10 samples). The results in (E) represent the relative expression of total CD79b protein in U-CLL samples vs M-CLL samples with total CD79b protein expression in U-CLL samples set at “1.0” (lines represent mean ± SEM of 11 samples). **P < .01; ***P < .005. NB, naïve B cell; NS, not significant.