p. every 2 days starting at day 0 and continued until the mice were killed. Either 1 mg anti-IL-10R (1B1.3a) mAb or control rat IgG was injected i.p. on day 0. Starting in the second week, 500 μg anti-IL-10R mAb or rat IgG was injected twice weekly and continued until killing. Mice in all groups were immunized with antigen on day 0. Sheep red blood cells were purchased from Colorado Serum Company, Denver, CO and 200 μl 10% volume/volume

SRBC solution (equivalent to 1 × 108 to 5 × 108 SRBC) was injected i.p. Mouse-adapted influenza A virus (IAV; A/Puerto Rico/8/34 H1N1), prepared by Dr Kevin Legge, was injected i.p. at a dose of 3 × 106 mean tissue culture infectious units in 100 μl PBS. R-Phycoerythrin (R-PE) was obtained from Chromaprobe (Maryland Heights, MO) and 100 μg Tanespimycin in vivo R-PE was Dabrafenib cell line precipitated in alum and injected i.p. Spleens were minced, washed with balanced salt solution, and viable mononuclear cells were obtained using density centrifugation over Fico/Lite-LM (Atlanta Biologicals, Norcross, GA). Cells were resuspended in staining buffer (balanced salt solution, 5% bovine calf serum and 0·1% sodium azide).

To stain for multi-parameter flow cytometric analysis, 1 × 106 to 2 × 106 cells were added to 10 μl rat serum (Pel Freez, Rogers AR) and 10 μg of 2.4G2 (anti-CD16/32) to minimize background staining mediated by Fc receptor binding. Rat anti-mouse mAbs used for staining were anti-IgM (b76), anti-B220 (6B2), anti-CD4 (GK1.5), anti-CD25 (7D4), anti-GITR (DTA-1), anti-CXCR5 (biotin conjugate; BD Pharmingen, San Diego, CA) and anti-CCR7 (PE-Cy7 conjugate; eBioscience, San Diego, CA). The FITC-conjugated and unconjugated peanut agglutinin (PNA), specific for terminal galactosyl (1,3) N-acetylgalactoseamine residues, was obtained from Vector Laboratories (Burlingame, CA), and R-PE-conjugated streptavidin was purchased from Southern Biotechnology Associates (Birmingham, AL). 2.4G2, b76, 6B2, GK1.5, 7D4 and DTA-1 mAbs were semi-purified from

HB101 serum-free supernatants by 50% ammonium sulphate precipitation. The mAbs and PNA were conjugated to biotin (Sigma-Aldrich, St Louis, MO) or Cy5 (Amersham Pharmacia, Piscataway, NJ) using standard procedures. Purified rat IgG (Jackson Immunoresearch Laboratories) was similarly conjugated and used for isotype controls. The appropriate primary mAbs or ADAM7 PNA-FITC were added to cells and incubated for 20 min on ice. When using anti-CXCR5 and anti-CCR7 mAbs to stain T cells, the primary incubation was 30 min at 37°. Cells were washed twice in staining buffer, and secondary streptavidin reagent was added to detect biotinylated antibodies. Cells were again incubated on ice for 20 min, washed twice in staining buffer, and resuspended in fixative (1% formaldehyde in 1·25 × PBS). Flow cytometric analysis was performed on a FACSCanto II (Becton Dickinson, San Jose, CA). For most experiments, 1 × 105 to 5 × 105 cells were collected per sample.