Efferocytosing macrophages produce IL-4 in vitro. (A) WT mouse PEMs were isolated from WT B6 mice 3 days after intraperitoneal injection of sodium periodate and co-cultured with human ACs at 1:5 (mac:particle) ratio for 18 hours. IL-4 produced was determined by ICS using anti-IL-4 or isotype. F4/80 staining was used to label macrophages. (B) Amounts of IL-4 in supernatants from co-culture in (A) with ACs were measured by multiplex. (C-D) mRNA levels of Il4 (C) and the transcription factors Gata3 and Irf4 (D), in efferocytosing macrophages were measured by quantitative reverse transcriptase-polymerase chain reaction 9 hours after co-culture with ACs. (E-F) After co-culture of PEM with ACs for 24 hours, cell surface expression of IL-4Rα and major histocompatibility complex class II were determined by antibody staining followed by flow cytometry. Data represent at least 3 independent experiments.