Ahluwalia, J. and Tinker, A. and Clapp, L.H. and Duchen, M.R. and Abramov, A.Y. and Pope, S. and Nobles, M. and Segal, A.W. (2004) The large-conductance Ca2+ -activated K+ channel is essential for innate immunity. Nature , 427 (6977) pp. 853-858. 10.1038/nature02356.
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Neutrophil leukocytes have a pivotal function in innate immunity. Dogma dictates that the lethal blow is delivered to microbes by reactive oxygen species (ROS) and halogens1, 2, products of the NADPH oxidase, whose impairment causes immunodeficiency. However, recent evidence indicates that the microbes might be killed by proteases, activated by the oxidase through the generation of a hypertonic, K+-rich and alkaline environment in the phagocytic vacuole3. Here we show that K+ crosses the membrane through large-conductance Ca2+-activated K+ (BKCa) channels. Specific inhibitors of these channels, iberiotoxin and paxilline, blocked oxidase-induced 86Rb+ fluxes and alkalinization of the phagocytic vacuole, whereas NS1619, a BKCa channel opener, enhanced both. Characteristic outwardly rectifying K+ currents, reversibly inhibited by iberiotoxin, were demonstrated in neutrophils and eosinophils and the expression of the -subunit of the BK channel was confirmed by western blotting. The channels were opened by the combination of membrane depolarization and elevated Ca2+ concentration, both consequences of oxidase activity. Remarkably, microbial killing and digestion were abolished when the BKCa channel was blocked, revealing an essential and unexpected function for this K+ channel in the microbicidal process.
|Title:||The large-conductance Ca2+ -activated K+ channel is essential for innate immunity|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute of Child Health > Department of Genes, Development and Disease > ICH - Molecular Medicine Unit|
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