FIGURE 4.

The hyperresponsive phenotype of Neu5Gc-null T cells. A, splenic T cells from wild-type (black/line) and Cmah^−/− (gray/filled) mice were stimulated with ConA (5 μg/ml) or with anti-CD3 (0.5 μg/ml) and anti-CD28 (0.5 μg/ml) antibodies. After 2 days, cells were stained with anti-CD25 or anti-CD69 antibodies and analyzed by flow cytometry. Data are representative of three independent experiments that yielded similar results. B, splenic T cells of wild-type and Cmah^−/− mice were stained with FITC-conjugated ConA. Gray dashed lines, negative control values. Data are representative of three independent experiments that yielded similar results. C, splenic T cells of wild-type (open columns) and Cmah^−/− (filled columns) mice were stimulated with the indicated concentrations of ConA or of anti-CD3 and anti-CD28 antibodies for 24 h, and BrdU was then added. After overnight incubation, incorporated BrdU was detected by ELISA, and it is expressed in chemiluminescence units. None, unstimulated samples. Data are the means of values from triplicate cultures. Error bars, S.E. Data are representative of more than three independent experiments that yielded similar results. *, difference between the test and control data was statistically significant by Student's t test (p < 0.01).