Plasmacytic differentiation and Ig secretion.(A-B) Real-time analysis of Bcl-6 and Blimp expression from splenic B cells cultured in vitro with IL-4 either with or without hCD40L stimulation for 24 hours and 5 days, respectively. Relative expression of various gene targets normalized to β-actin was calculated as (2^{−(experimental CT − β-actin CT)}) × 1000, where CT is the cycle threshold of signal detection. (C-D) IgM and IgG secretion from B cells was accessed by ELISA analysis using supernatant collected from 5 days of in vitro culture of splenic B cells with or without 400 ng/mL hCD40L and 10 ng/mL IL-4 (*P = .004; **P = .001). Data are representative of 3 independent experiments (mean ± SD).