Figure 6. CD4⁺ T cell-specific deletion of IL4ra attenuated neonatal RSV infection-induced Th2 responses upon reinfection.

Th-specific, IL-4Rα-deficient (Lck^creIL4Rα^−/Lox-RR) and -competent mice (IL4Rα^−/Lox-RR) were infected at 5 days of age and reinfected with RSV at 4 weeks postprimary infection. Control mice of each genotype were treated with serum-free medium (Lck^creIL4Rα^−/Lox-sham and IL4Rα^−/Lox-sham, respectively). Pulmonary Th profile and BALF cellularity and cytokine levels were measured at 6 days postsecondary infection. (A) Pulmonary Th profile. Lung cells were isolated, stimulated, and stained with dead cell, excluding dye and antibodies to CD3, CD4, IFN-γ, and IL-4. The cells were then analyzed by flow cytometry; n = 3–7. (B) Representative dot plots showing the IL-4- and IFN-γ-expressing Th cells. (C) BALF cellularity; n = 5. (D) Cytokine levels in BALF; n = 4–12; *P < 0.05.