IL-4 priming of MΦs does not modify SRA and MARCO expression or decrease N meningitidis binding at MΦ surface. (A) Effect of IL-4 on N meningitidis binding at the MΦ surface. ThioMΦs were treated for 48 hours with IL-4 and incubated for 2 hours at 4°C with RdGnX-N.m. (Nm; 100 bacteria/MΦ). The average mean fluorescence intensity of 2 independent experiments is presented as a bar diagram. Error bars indicate SDs. (B) Effect of IL-4 on surface expression of SRA and MARCO. ThioMΦs were treated for 48 hours with IL-4, and SRA and MARCO cell surface expressions were determined by flow cytometry using αMARCO mAb (ED31) or αSRA mAb (2F8). One experiment representative of 2 is shown. (C) Effect of alternative activation on RdGnX-N.m. uptake by WT, SRA^−/−, MARCO^−/−, and SRA^−/−/MARCO^−/− MΦs. ThioMΦs were treated for 48 hours with IL-4 and incubated for 2 hours at 37°C with RdGnX-N.m. (100 bacteria/MΦ). The average mean fluorescence intensity for 4 independent experiments is presented as a bar diagram. Error bars indicate SDs.