Several studies show that the risk of granulomatous infections following therapy with the anti-tumor necrosis factor (TNF) antibody infliximab is higher than after treatment with the soluble TNFRp75 immunoglobulin fusion construct etanercept. Therefore, despite sharing a common target, it is possible that the actual mode of action of the 2 biologicals differs in vivo. TNF is known to participate in the induction and maintenance of protective granulomas at multiple steps, and evidence supporting a differential inhibition of TNF bioactivity and signaling by the 2 drugs is discussed.