Aspirin significantly decreases the nonopsonic phagocytosis and immunogenicity of macrophages in mice

Objective and design: The effect of acetylsalicyclic acid (ASA) on the phagocytosis and immunogenicity of macrophages remains to be determined. Material or subjects: BALB/c mice and peritoneal macrophages were used. Treatment: BALB/c mice were treated with ASA (0, 6, or 60 mg/kg/day) intraperitoneally for 1 week. Methods: Flow cytometry and phagocytosis assay were employed. Results: ASA significantly decreased cell numbers, non-opsonic phagocytosis, and immunogenicity as well as changing the phenotypes of peritoneal macrophages in vivo. After in vitro treatment with ASA, macrophages expressed low levels of MHC-II, CD80, and CD47 molecules, and showed significantly decreased phagocytosis. Importantly, ASA blocked the differentiation of macrophages from bone marrow cells in vitro as indicated by decreased macrophage cell numbers and phenotype alteration. Conclusions: The present study provides basic information on the direct effect of ASA on macrophages, supporting the potential application of ASA in patients with allo-grafts or autoimmune diseases.