TNF-α augments human antibody reactivity against Neu5Gc-loaded endothelium. Endothelial cells were treated with TNF-α (10 ng/mL) during the last 18 hours of Neu5Gc loading. Antibody binding was assessed for both treated and nontreated cells after incubating with high-titer human serum (S34). Control peaks represent staining with FITC-conjugated secondary antibody alone. The experiment was performed multiple times and representative examples are shown. Several other cytokines studied (IL-1β, IL-4, IL-6, IL-13, and IFNγ) did not show this enhancing effect (not shown).