Expression of IL-12R mRNA in primary B cells. IL-12Rβ2 (A) and IL-12Rβ1 (B) PCR curves for untreated purified primary B cells. In panels C and D, quantitative PCR was used to measure IL-12Rβ2 and IL-12Rβ1 mRNA expression (see “Materials and methods”) following activation with IFN-γ, IL-12, or anti-CD40 for 24 hours. Results (means ± SEMs) are expressed as -fold increases in normalized cDNA values of IL-12Rβ2 (C) and IL-12Rβ1 (D) versus the level in untreated cells. 0-PCR indicates PCR controls without cDNA; 0-RNA, RT-PCR controls without RNA; 0-RT, RT-PCR controls with RNA but without reverse transcriptase.