Effect of TNFR55 blocking antibodies on TNFR55-selective mutant-induced neutrophil apoptosis. Human neutrophils (5 × 10⁶/mL) were preincubated in the presence (▨) or absence (▪) of antihuman TNFR55 MoAbs before stimulation with medium alone (control), 12.5 ng/mL TNF-α, or 100 ng/mL of the TNFR55 selective mutant proteins E146K or RWS86T for 6 hours. The extent of apoptosis was assessed morphologically. Data represent mean ± SEM of three separate experiments, each performed in triplicate.