FIG. 3.

IL-12-mediated p38 MAP kinase activation contributes to IFN-γ production by effector Th1 cells. (A and B) CD4⁺ T cells were purified from C3H mice infected for 2 weeks, and they were restimulated with a B. burgdorferi lysate (Bb) in the absence or presence of a blocking MAb to IL-12 (αIL-12) (10 μg/ml) (A) or recombinant murine IL-12 (10 ng/ml) in the absence or presence of SB203580 (SB) (5 μM) (B) for 40 h. (C) Cells were also stimulated with anti-CD3 (αCD3) (5 μg/ml) in the absence of antigen-presenting cells and in the absence or presence of IL-12 and SB203580. The supernatants were analyzed to determine IFN-γ levels by ELISA. The results are representative of the results of three independent experiments. An asterisk indicates that the P value is <0.001, as determined by Student's t test.