Blocking RGD-binding integrins modulates macrophage cytokine secretion in response to fibronectin-opsonized, LPS-coated UHMWPE microparticles (MPs). Secreted cytokines: A.) IL-6, and B.) TNF-α, from macrophages in response to 24 h exposure to fibronectin-opsonized, LPS-coated (5 EU/million MPs-mL) MPs with or without RGD blocking with 10 mM soluble peptide. Positive control of soluble LPS (1μg/ml) and a negative control of macrophages cultured without MPs was included. Cytokine concentrations were quantified by pooling data from 6 samples from 2 separate runs. Plotted are mean and standard error. Uppercase letters denote significant differences (p < 0.05) among all groups analyzed by ANOVA and Tukey’s post hoc test, where groups labeled with a differing capital letters are significantly different from each other, and groups with identical capital letters are not.