Effect of APC inhalation on allergic airway inflammation. (A) Eosinophil count (black bar) in BALF was significantly high in the OVA + SAL group compared with the OVA + APC group. No difference was found in the number of lymphocytes (white bar) or macrophages (gray bar). BALF concentrations of total protein (B), IL-4 (C), IL-13 (D), IL-5 (E), and thrombin (F) were significantly decreased in the OVA + APC group compared with the OVA + SAL group. The IL-5/IFN-γ (G; black bars) ratio was significantly decreased, whereas the BALF IFN-γ (G; white bars) level was significantly increased, in the OVA + APC group compared with the OVA + SAL group. There was not a significant difference in BALF nitrate/nitrite ratio (H) between the OVA + APC and OVA + SAL groups. Stimulation of lymphocytes isolated from murine lymph nodes with OVA alone significantly enhanced the concentrations of IL-4 (I), IL-5 (J), and IL-13 (K) in the culture supernatants. APC significantly suppressed the concentrations of IL-4, IL-5, and IL-13 in a dose-dependent manner. APC alone exerted no influence on the expression of any of these cytokines. RT-PCR (L) showed that APC significantly decreased the relative abundance of IL-4, IL-5, and IL-13 mRNAs in OVA-stimulated mouse lymphocytes in a dose-dependent manner. Data represent the mean ± SD of values obtained in 6 mice. *P < .05, compared with the OVA + SAL or OVA group. **P < .001, compared with the OVA + SAL or OVA group.