Quantitation of C, IL-2, and IL-10 mRNA by RT-PCR amplification. At sequential cycle numbers, cDNA PCR samples synthesized from mRNA, prepared from adult spleen (□), adult BM (▪), and NBB (⧫). Con A-stimulated cells were collected and transferred onto avidin-coated microtiter plates. Quantitation of the amplified products was performed in a liquid-hybridization–ELISA assay with luminometry readings.