Fig. 5.
Retinoic acid downregulates CD40 + IL-4–mediated epsilon germline transcription. Human peripheral B cells were stimulated for 4 days in the presence of anti-CD40 + IL-4 (1 μg/mL and 5 ng/mL), respectively, alone or in combination with all-trans RA (10−14, 10−12, 10−10 mol/L). Thereafter, mRNA was extracted. C germline and GAPDH transcripts were assessed by semiquantitative RT-PCR.