Immunization with particulate Ag-CpG enhances specific antibody responses and promotes class switching to IgG2 isotypes. (A) C57BL/6 mice (3 mice per group) were immunized once with either 1 μL OVA-CpG–coated particles with 1 μL CγG-coated particles or 1 μL CγG-CpG particles with 1 μL OVA-coated particles. Serum CγG- (left panel) and OVA-specific IgG (right panel) were measured 14 days after immunization. Data are representative of 2 independent experiments. (B,C) C57BL/6 mice were immunized with 10 μL of either particulate CγG alone, particulate CpG alone or particulate CγG-CpG. (B) CγG-specific IgG subtypes were determined by ELISA 14 days after immunization; (C) ELISPOTs were used to quantify the number of bone marrow CγG-specific IgG secreting ASCs 14 days and 3 months after immunization. Values represent the mean (± SD) from triplicate samples.