(A) Peritoneal macrophages were harvested from hCD20/NOD mice 1 month after 2H7 or IgG treatment and used as APCs after irradiation in a proliferation assay with BDC2.5 CD4 cells responding to BDC2.5 mimotope or 6426 cloned CD8 T cells responding to 9-mer insulin B chain peptide of amino acid position 15–23 (B15–B23). ³H-thymidine incorporation is presented as Δ cpm (cpm in the presence of antigenic peptide minus cpm in the absence of antigenic peptide). Macrophages from 2H7-treated mice presented peptides poorly to both CD4 and CD8 T cells compared with macrophages from IgG-treated mice (P < 0.005). (B) One month after 2H7 or IgG treatment, splenic CD11c⁺ DCs of hCD20/NOD mice were used as APCs after irradiation. 6426 CD8 cloned T cells were cultured with irradiated DCs in the presence or absence of 9-mer insulin B chain peptide of amino acid position 15–23 (B15–B23) (at 3 μg/ml) in a ³H-thymidine incorporation proliferation assay. (C) Splenic CD11c⁺ DCs were purified from hCD20/NOD mice 1 month after 2H7 or IgG treatment and used as APCs after irradiation. Purified splenic BDC2.5 CD4 T cells were cultured with irradiated DCs in the presence or absence of BDC2.5 mimotope. IL-2 production was measured by cytotoxic T lymphocyte line (CTLL) assay in culture supernatants after a 48-hour incubation.