Figure 5.

Sildenafil down-regulates IL-4Rα expression on CD11b⁺ cells. CD4⁺, CD8⁺, CD11b⁺, or CD11c⁺ cells were magnetically purified from spleens of C26GM-bearing mice challenged 9 d earlier. CD4⁺ or CD8⁺ T cells were stimulated with ConA for 3 d, with or without 50 μg/ml sildenafil. (A) Purified cells were cultured separately for 2 d with or without sildenafil, harvested, and used to determine cGMP levels, as described in Materials and methods. (B) T cell proliferation was determined by [³H]thymidine incorporation. (C) CD11c⁺ cells were analyzed for B7.2 and MHC class II expression. (D) CD11b⁺ cells were analyzed for IL-4Rα expression by flow cytometry. The t test p-value is reported. Error bar values are shown. MFI, multiplicity of infection.