Production of IgG2b and IgG3 antibodies by MZ B cells in vitro. FO and MZ B cells were sorted by FACS from wild-type C57BL/6 mice. The cells were then cultured with anti-CD40 and IL-4 to induce IgG1 class switching, LPS and IFNγ to induce IgG2c class switching, or LPS to induce IgG2b and IgG3 class switching. The culture supernatants were collected after 4 days of culture, and different isotypes of antibodies were measured by ELISA. Results are representative of at least 3 independent experiments.