Antibody-dependent phagocytosis of haptenated liposomes by human neutrophils is dependent on the physical state of the liposomal membrane.
In the present study we have examined the response of human neutrophils to specific antibody-dependent stimulation by spin-label haptenated fluid phase and solid phase liposomes. Both fluid and solid liposomal antigens are shown to stimulate the neutrophil respiratory burst to approximately equivalent degrees as assessed by measurement of oxygen consumption or oxidation of [1-14C]glucose to 14CO2. In contrast, release of superoxide and hydrogen peroxide from the neutrophils is stimulated to a significantly greater degree by fluid-phase liposomes than by the equivalent solid-phase liposomes. This apparent discrepancy is shown to be due to an inability of the neutrophils to phagocytose fluid-phase liposomes under conditions in which solid-phase liposomes are readily phagocytosed. A fluorescence assay, which does not depend upon binding measurements, has been developed in order to quantitate liposomal phagocytosis.
D000906:Antibodies; D005455:Fluorescent Antibody Technique; D006241:Haptens; D006801:Humans; D066298:In Vitro Techniques; D008081:Liposomes / Q000276:immunology*; D008560:Membrane Fluidity; D009504:Neutrophils / Q000276:immunology* / Q000378:metabolism; D010101:Oxygen Consumption; D010587:Phagocytosis
D000906:Antibodies; D006241:Haptens; D008081:Liposomes