Intracellular IL-4 is reduced in X-CGD RPMØs and is required for efficient efferocytosis. (A) Freshly isolated F4/80-positive RPMØs were analyzed for intracellular IL-4 (compared with isotype control) by flow cytometry; histograms are representative of N = 8. (B) RPMØs were plated for 24 hours and treated with 10 ng/mL IL-4 or IL-13 and/or 500 ng/mL neutralizing antibody to IL-4 or isotype control antibody for 20 hours before performing efferocytosis assays. Data represent means plus or minus SEM; N = 5 experiments. *P ≤ .005 compared with untreated WT; #P ≤ .005 compared with untreated X-CGD; and Δ, P value less than or equal to .005 compared with α-IL-4–treated WT. Significant differences demonstrated in Figures 1 and 2 were maintained but not designated for clarity.