Effect of anti–SNAP-23 and anti–syntaxin 6 antibodies on the up-regulation of CD63 and CD67 cell surface expression in activated electropermeabilized human neutrophils.

Electropermeabilized human neutrophils (PMNs) were incubated for 3 minutes at room temperature in the absence (Control) or in the presence of CD20 MoAb (2 μg/ml) or in the presence of increasing concentrations (8, 16, and 20 μg/mL) of anti–SNAP-23 and anti–syntaxin 6 antibodies. Cells were then incubated with 5 μg/mL cytochalasin B for 5 minutes at 37°C and activated with 1 μmol/L Ca⁺⁺ and 50 μmol/L GTP-γ-S for 10 minutes at 37°C. Subsequently, cells were fixed with 1% paraformaldehyde for 2 minutes at room temperature and treated as described in “Materials and methods” for CD63 and CD67 cell surface expression. Data are expressed as percentage of the increase of CD63 and CD67 cell surface expression on electropermeabilized PMN activation compared with regard to the up-regulation of CD63 and CD67 detected in control Ca⁺⁺ and GTP-γ-S–stimulated electropermeabilized neutrophils in the absence of any antibody (Control), considered as 100% of increase in cell surface antigen expression. Mean values ± SD of 3 independent determinations are shown.