Downmodulation of anti-CD40–induced IL-12 secretion after anti-CD3ɛ treatment. Unselected spleen cells (106cells/well) from control and anti-CD3ɛ–injected mice (48 hours posttreatment, 50 μg IV) were stimulated in vitro by an activating rat IgG2a anti-CD40 MoAb (3 μg/mL) or an equivalent amount of an isotype-matched, control antibody (clone IR418). When indicated, cultures were supplemented with a neutralizing antibody to the IL-12 subunit p40 (rat IgG2a C17.8, 5 μg/mL) or with an equivalent amount of an isotype-matched, control antibody (clone IR418). Supernatants were harvested 48 hours later and assayed as described in Materials and Methods. The results represent the mean of 3 independent cultures (assayed in duplicate) and are representative of 3 independent experiments. The detection limit of the assay was 0.2 pg/mL.
