Ova 488

For CD169⁺ macrophages isolation, spleens digested with 1 Wu/mL liberase TL (Roche Diagnostics), 4 mg/mL lidocaine hydrochloride monohydrate (Sigma), and 50 μg/mL DNAse (Roche Diagnostics) in PBS at 37°C. Staining was performed with mAbs listed in Supporting Information after blocking Fc receptor with clone 2.4G2. All Abs for extracellular stainings were diluted at the appropriate concentration in PBS containing 0.5% BSA. Abs were incubated for 30 min at 4°C. GC B cells were detected with the use of 5 μg/mL OVA‐488 (Invitrogen) incubated together with the primary Abs. For intracellular staining (Figs. 3B, 4A, and B) cells were fixed in PBS containing 2% paraformaldehyde and stained subsequently in PBS supplemented with 0.5% BSA and 0.5% saponine. Sytox blue nucleic acid stain (Invitrogen) or LIVE/DEAD® Fixable Near‐IR Dead Cell Stain Kit (Invitrogen) were used according to the manufacturers’ protocol. Cells were analyzed using a Cyan ADP flow cytometer (Beckman Coulter) and the Flowjo software package (Tree Star).