IL gene expression in adult spleen, BM, and in NBB. Cells from spleen, BM, and NBB were stimulated with Con A for 24 hours and mRNA extracted. Semiquantitative RT-PCR amplification was performed on cDNA using C-, IL-2–, IFNγ-, IL-4–, and IL-10–specific primers. PCR products were analyzed on agarose gel after 35, 40, and 45 cycles of amplification.