Effects of influenza A virus on human neutrophil calcium metabolism.
Bacterial superinfection in influenza A virus-related illness may in part be explained by virus-induced neutrophil dysfunction. We here provide evidence that this effect is related to abnormal calcium metabolism of virus-infected cells. Neutrophils exposed to influenza virus for 0.5 h at 37 degrees C showed depressed O2- generation and release of radiolabeled arachidonic acid upon stimulation with FMLP. The peak cytosolic Ca2+ level achieved by virus-infected neutrophils after FMLP stimulation was significantly depressed as is efflux of 45Ca2+. This deficient Ca2+ mobilization could not be attributed to alterations of inositol phosphate production or Ca2+ influx in response to FMLP, both of which were unaffected by prior virus infection. Given these findings, the immediate effects of influenza virus on neutrophil Ca2+ metabolism were examined. The virus itself caused a rise in cytosolic Ca2+ and an efflux of 45Ca2+ without any corresponding 45Ca2+ influx. Total cell Ca2+ however was not depleted as measured by atomic absorption. Influenza virus, therefore, causes neutrophil activation leading to significant perturbations in Ca2+ metabolism and later to impaired mobilization of Ca2+ stores. This system offers a model for phagocyte deactivation and an opportunity to define control mechanisms of signal transduction.
D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D006801:Humans; D009980:Influenza A virus / Q000502:physiology*; D007295:Inositol Phosphates / Q000378:metabolism; D007424:Intracellular Fluid / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine; D009504:Neutrophils / Q000378:metabolism* / Q000382:microbiology / Q000502:physiology; D010101:Oxygen Consumption
D001095:Arachidonic Acids; D007295:Inositol Phosphates; D016718:Arachidonic Acid; D009240:N-Formylmethionine Leucyl-Phenylalanine; D002118:Calcium