Incubation of macrophages with IVIg at phagocytosis-inhibiting concentrations does not lead to an increased FcγRIIb expression. (A) Staining with MoAb 2B6, corrected for isotype control, in M-CSF or GM-CSF macrophages cultured for 9 days left either unstimulated (circles) or stimulated with 10 μg/mL (upper) or 100 μg/mL (lower) IVIg for 2 days (triangles). (B) FCGR2B2 mRNA expression compared with expression of housekeeping gene GUS, in M-CSF or GM-CSF macrophages cultured for 9 days, left either unstimulated (circles) or stimulated with 100 μg/mL IVIg for 2 days (triangles). Dots represent individual measurements, with lines linking the paired experiments with cells of the same individual. P values in this figure were determined using 2-way ANOVA.