TLR2-stimulated IL-6 production is associated with the Why1 locus. (A) Codominant inheritance of IL-6 protein secretion. Peritoneal macrophages from parental strains and F1(C57BL/6JxMOLF/Ei) hybrid mice were plated and stimulated for 6 h with the indicated concentrations of LTA. IL-6 secretion was measured by ELISA. Results are ± SEM from triplicate wells, representative of three independent experiments. (B) Peritoneal macrophages from 82 N2 (C57BL/6Jx(C57BL/6JxMOLF/Ei)) mice were plated and stimulated with 2 µg/ml LTA as in A. Mean IL-6 production from triplicate wells is plotted for each mouse, grouped by genotype at D6MIT328, a marker near the peak of the Why1 locus. (C) Peritoneal macrophages from 50 independent N2 backcross mice were stimulated for 1 h with 2 µg/ml LTA. IL-6 mRNA was quantified by real time PCR. Mean mRNA production from two wells is plotted, grouped by genotype at D6MIT328. P-values were calculated in B and C using a two-tailed Student's t test.