Response of naïve T cells to stimulation.

<p>(A) CD4+ T cells isolated from unsensitized WT and SHIP-1^−/− mice were incubated with medium, α-CD3, or α-CD3/α-CD28 for 24 hr and the levels of IL-4 in the culture medium were determined by ELISA (n = 5 each group, ***p<0.001). (B) Naïve CD4+ T cells isolated from WT and SHIP-1^−/− mice were incubated with negatively selected, irradiated APC from the spleen of WT or SHIP-1^−/− mice in different ratios in the presence of OVA_323–339 and IL-4 production was determined (n = 4 for each group).