RNA interference. (A) The inhibition of endogenous IL-24 expression resulted in increased plasma cell numbers in GC B-cell cultures. Cell-sorted GC B cells (10⁷) from 2 tonsils were transfected with 100nM control or IL-24–specific siRNAs, cultured the day after with IL-2 + IL-10 + CD40L for 3 days and with IL-2 + IL-10 for 4 more days, and cells were stained with CD38 and CD20 MAbs. (B) Western blot was performed in parallel at day 3 and shows the inhibition of IL-24 but not of STAT-3 protein expression in cells treated with IL-24–specific siRNA; control (random) RNA had no effect. (C) The efficacy of transfer was monitored by cotransfection of PE-random siRNA siGLO and IL-24–specific siRNA at a 1:5 ratio.