RESUMO
OBJECTIVE To study the effects and potential mechanism of anaphylactoid reaction induced by nonapeptide IVQKIKHCF activating mast cells. METHODS Using human mast cell line LAD2 as subject， and substance P as positive control， the activation effects of 25， 50 and 100 μmol/L IVQKIKHCF on mast cells were investigated by determining the release rate of β-aminohexosidase， histamine release， and the contents of inflammatory factors； using MrgprX2-knockdown LAD2 cells and Mas- related G protein-coupled receptor X2 （MRGPRX2） high-expression human embryonic kidney cell line HEK293 （MRGPRX2/ HEK293 cells） as subject， the correlation between the activation effect of IVQKIKHCF and MRGPRX2 was investigated by determining the release rate of β-aminohexosidase， and intracellular calcium ion concentration. RESULTS IVQKIKHCF with 25， 50， 100 μmol/L could significantly increase the release rate of β-aminohexosidase and histamine release in LAD2 cells （P＜0.05）， and promote the release of tumor necrosis factor-α， interleukin-8， macrophage inflammatory protein-1β and monocyte chemotactic protein-1 to varying degrees （P＜0.05）. After knocking down MrgprX2， the effects of 25， 50， 100 μmol/L IVQKIKHCF promoting the release of β-aminohexosidase in LAD2 cells were reversed significantly （P＜0.05）， resulting in an increase of calcium ion concentration in MRGPRX2/HEK293 cells. CONCLUSIONS Nonapeptide IVQKIKHCF can promote mast cells to release granular matter and inflammatory mediators by activating MRGPRX2 thus inducing anaphylactoid reaction.