Effect of complement opsoneation on immune complex-induced metabolic oscillations in migrating neutrophils

Cells exhibit sinusoidal 3 min. oscillations in metabolite (NADH, ATP, etc.) concentrations. In addition to the 3 min. oscillation, we have recently found that migrating neutrophils possess a 12 or 22 sec. metabolic oscillation, depending upon cell stimulus. To better understand the mechanisms of 1C interactions with leukocytes, we have studied neutrophil metabolic oscillations in the presence of soluble or precipitate forms of ICs (BSA and anti-USA) which were or were not treated with complement (SO ug/ml). One convenient means of monitoring metabolite levels exploits the autofluorescence of NADH. Thus, we have used a microscopic photometer apparatus to quantitate metabolic oscillations. We found that soluble ICs gave an oscillation period of 12.7±2.1 sec. and 24.7±4.2 sec. (P<0.01) in the absence and presence of complement opsonization, respectively. 1C precipitates gave oscillation periods of 13.1±2.3 and 24.6±5.5 sec. (P<0.01) in the absence and presence of complement Untreated cells display a period of 22.3±2.3 sec. Control experiments showed that all complexes bound to cells. Thus, untreated ICs trigger rapid metabolic oscillations, as does FMLP; in contrast, complement-treated ICs did not affect oscillations. Thus, die state of complement activation, not IC size, is a principle factor in metabolic signaling. These factors may contribute to differences in leukocyte stimulation observed for complement treated and untreated ICs.