Fig. 4

A549 cell-derived exosomes induce mast cell activation, degranulation and tryptase release. a Mast cells were activated with A549 cell-derived exosomes carrying SCF, which led to an increased rate of hexosaminidase release. The release of cytokines into the supernatant of mast cells in the presence of A549 cell-derived exosomes at 24 h was detected by ELISA. MMP-9 (b), tryptase (c), TNF-α (d) and IL-6 (e) were significantly increased in the experimental group, which was significantly different from the control and inhibitor groups. f The supernatants of mast cells stimulated with SCF or A549 cell-derived exosomes were analyzed for tryptase and β-actin via Western blotting. g Relative intensity was calculated for tryptase. All of the above data are representative of three independent experiments (n = 3). P-values, * < 0.05, ** < 0.01