B-1 cells were isolated using flow cytometric cell sorting, as described previously [7]. Briefly, PECs were incubated with Fc block™ (BD Pharmingen, Franklin Lakes, NJ, USA) for 5 min at 4°C. For sorting of B-1 cells, this step was followed by staining with allophycocyanin (APC)-labelled anti-CD19 (clone 1D3), phycoerythrin (PE)-labelled anti-CD23 (clone B3B4) and fluorescein isothiocyanate (FITC)-labelled anti-CD3 (clone 17A2). For sorting of B-1a, B-1b and B-2 cells, Fc block incubation was followed by staining with FITC-labelled anti-CD23 (clone B3B4), PE-labelled anti-CD5 (clone BVD-523 molecular weight 53-7·3) and APC-labelled anti-CD19 (clone 1D3) (all antibodies from BD Pharmingen). B cell

populations were sorted using a fluorescence activated cell sorter (FACS) Aria II (BD Pharmingen) based on forward-scatter (FSC), side-scatter (SSC) and staining for CD3, CD5, CD19, CD23 as follows: B-1 cells: CD19+, CD3−, CD23−; B-1a cells: CD19+, CD23−, CD5dim; B-1b cells: CD19+, CD23−, CD5−; and B-2 cells: CD19+, CD23+, CD5−. Doublets were excluded using FSC-H, FSC-A. According to post-sort analysis, sorted B cell populations constituted >99% of all isolated cells. Isolated cells were seeded at 200 000 cells/ml in culture medium containing RPMI-1640 supplemented with 10% heat-inactivated FCS, 20 mmol/l HEPES, 2 mmol/l glutamine, 100 U/ml penicillin, 100 μg/ml streptomycin, 1 mmol/l sodium RXDX-106 pyruvate, 1 mmol/l nonessential amino acids and 0·05 mmol/l 2-mercaptoetanol (all Invitrogen, Carlsbad, CA, USA). As indicated for each experiment, cells were cultured at 37°C/5%

CO2 for 3 or 7 days in the presence of D-(+)-glucose (Sigma, St Louis, MO, USA) at the concentrations indicated (5·5, 25, 50 or 75 mmol/l), Kdo2-Lipid Thalidomide A (100 ng/ml) (Avanti Polar Lipids, Inc.), mannitol (75 mmol/l), insulin (200–10 000 pmol/l) or leptin (0·01–1 μg/ml). Cell counting was performed at the end of the culture using a Countess® Automated Cell Counter (Invitrogen, Life Technologies, Paisley, UK), according to the manufacturer’s instructions. For analyses of leucocyte populations in peritoneum and spleen, PEC were harvested as described above and splenocytes were collected on a mesh filter, using ice-cold PBS supplemented with 0·5% heat-inactivated FCS and 10 mmol/l EDTA. For cell surface staining, PECs, single cell splenocyte suspensions or cultured B-1 cells were incubated with Fc block™ (clone 2·4G2) for 5 min at 4°C, followed by staining for 30 min as follows. Peritoneal cells were stained with FITC-labelled anti-CD23 (clone B3B4), peridinin chlorophyll-cyanin 5·5 (PerCP-Cy5·5)-labelled anti-CD11b (clone M1/70), PE-labelled anti-CD5 (clone 53-7·3), APC-labelled anti-CD19 (clone 1D3) and PE-Cy7–labelled anti-IgM (clone R6-60·2).