Figure 1.

IVIG induces cell death in human but not in mouse polymorphonuclear neutrophils (PMNs) ex vivo. Death of human (PMN^H), C57BL/6 (PMN^BL/6) or BALB/c (PMN^BALB/c) mouse neutrophils in the presence or absence of priming with species matched GM-CSF, as assessed by flow cytometric ethidium bromide exclusion assay. (A) Different commercial IVIG/SCIG preparations similarly induce death of human peripheral blood neutrophils, an effect that is enhanced in GM-CSF primed cells. No death is induced in mouse PB neutrophils. (B) Comparison of the concentration-effect curves of IVIG in PB PMN^H or PMN^BL/6 with or without GM-CSF priming. (C) In mouse neutrophils from both strains, no IVIG-mediated death is observed, neither in cells derived from peripheral blood (PB) nor bone marrow (BM). (D) In in vivo primed neutrophils isolated from spleen or peripheral blood (PB) no IVIG-induced cell death was observed. Results of 24-h cultures are shown. Bars show mean ± SEM. Data are representative of at least 3 (D), 4 (C), 5 (B), or 6 (A) independent experiments. *p < 0.05, **p < 0.01, Student t test. Specific death was calculated in comparison to untreated controls as outlined in the Materials and Methods section.