FIG. 6.

Suppression of DTH by ABF is mediated by IL-4. IL-4-deficient (IL-4 KO) mice were used. (A) IL-4 KO mice and wild-type controls were immunized with OVA alone or in combination with 250 μg of ABF. Challenge occurred 7 days later with HAO, and the DTH responses were assessed over the subsequent 24 h. The members of the unimmunized control group (group 0) were challenged with only HAO. The DTH responses are expressed as the mean + standard error of the mean increase in footpad thickness for five mice per group. Serum and PLN cells were harvested 7 days postchallenge and stimulated with 50 μg of OVA per ml. (B to D) Total serum IgE levels (B) and IFN-γ (C) and IL-10 (D) production were determined after 24 h of in vitro culture. The data in panels C and D were obtained with pooled cells as insufficient numbers of cells could be obtained from individual animals. The data in panels A and B are means + standard errors of the means for five mice per group. An asterisk indicates that there was a significant difference compared to the value for the unsensitized group (P ≤ 0.001). ND, none detected.