Effect of zinc and other cations on the release of the eosinophil cationic protein.
The eosinophil cationic protein, ECP, is a unique eosinophil granule constituent, which is released extracellularly after exposure of the eosinophils to a non-phagocytosable surface such as complement-coated Sephadex beads. The ECP is released to some extent even in the absence of Ca2+ and Mg2+, though both these cations augment the release reaction tested alone, and an optimal release is observed only in the presence of 2 mmol/l Ca2+ and 2 mmol/l Mg2+ in the medium. Zn2+ at concentrations from 0.25-4.0 mmol/l inhibited the release of ECP in a dose-dependent fashion, with or without Ca2+ and Mg2+ in the medium. Mn2+ had dual effects, stimulating the ECP release in the absence of Mg2+ and Ca2+, and inhibiting the release in the presence of these cations. Li1+ caused minor inhibition of ECP release, but only in the absence of Ca2+ and Mg2+. The inhibitory effect of Zn2+ was immediate and reversible after washing of the cells, suggesting that the inhibition is due to interaction with the plasma membrane functions.
D001798:Blood Proteins / Q000032:analysis / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002458:Cell Fractionation; D047091:Eosinophil Granule Proteins; D004804:Eosinophils / Q000378:metabolism; D006801:Humans; D008094:Lithium / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D012260:Ribonucleases; D012636:Secretory Rate / Q000187:drug effects; D015032:Zinc / Q000494:pharmacology*
D001798:Blood Proteins; D047091:Eosinophil Granule Proteins; D008094:Lithium; D012260:Ribonucleases; D008274:Magnesium; D015032:Zinc; D002118:Calcium