Figure 1.

Staphopain A inhibits antibody binding to CXCR2 on neutrophils. (A) Neutrophils were incubated with 0.5 μM Staphopain A or buffer for 15 min at 37°C. After washing, cells were stained with a panel of blocking antibodies against surface-expressed receptors. The relative expression was calculated by dividing the mean fluorescence of Staphopain-treated cells by Buffer-treated cells. (B) Staphopain A blocks antibody binding in a dose-dependent manner. Neutrophils were incubated with various concentrations of Staphopain A for 15 min at 37°C and stained with an antibody recognizing the N-terminal domain of human CXCR2. Inlay: Representative histogram of the CXCR2 expression on neutrophils treated with 0.5 μM Staphopain A compared to buffer. (C) Protease activity is required for antibody inhibition. Neutrophils were treated with 0.5 μM Staphopain A with or without 1 μM Staphostatin A or 10 μM E64. All figures represent the mean±s.e. of three separate experiments using different donors. Background was determined using an isotype control. (A, B) *P<0.05 for Staphopain A versus buffer (two-tailed Student’s t-test); (C) *P<0.05 for Staphopain A plus inhibitor versus Staphopain A (two-tailed Student’s t-test).