Expression of IL-12Rβ2 in primary CD138⁺ MM cells. (A) IL-12RB1 and B2 expression in primary CD138⁺ MM cells, as assessed by RT-PCR. MW indicates molecular weight; NC, negative control (water in the place of cDNA); PC, positive control (total tonsil B cells); 11 MM cases (patients 1-11) are shown. (B) IL-12Rβ2 surface expression in primary CD138⁺ MM cells (patients 1 and 2), as assessed by flow cytometry using the mAb from BD Biosciences (BD mAb) or the Santa Cruz antibody (SC Ab). Open profile represents IL-12Rβ2 staining; dark profile, isotype-matched Ab staining. (C) Flow cytometric analysis of IL-12Rβ2 expression in PPCs generated in vitro (top panels), IL-12RB2-transfected Raji Burkitt lymphoma cells (middle panels), and a normal T helper 1 clone using the BD Bioscences mAb (left panels) and the Santa Cruz antibody (right panels). Open profile represents IL-12Rβ2 staining; dark profile, isotype-matched antibody staining.