AIM:To investigate the ability of histamine to modulatetryptase release from human colon mast cells and thepotential mechanisms.METHODS:Enzymatically dispersed cells from humancolons were challenged with histamine,anti-IgE or calciumionophore A23187(CI),and the cell supernatants afterchallenge were collected.Tryptase release was determinedwith a sandwich ELISA procedure.RESULTS:Histamine at concentrations from 1ng/mL wasable to induce a“bell”shape dose related release of tryptasefrom colon mast cells.The maximum release of tryptase wasapproximately 3.5 fold more than spontaneous release.Aslittle as 10ng/mL histamine showed a similar potency to10μg/mL anti-IgE in induction of tryptase release.Histamineinduced release of tryptase initiated at 10s when histamine(100ng/mL)was added to cells,gradually increasedthereafter,and completed at 5min.Both pertussis toxin ormetabolic inhibitors were able to inhibit histamine inducedtryptase release.When histamine and anti-IgE were addedto colon mast cells at the same time,the quantity of tryptasereleased was similar to that induced by anti-IgE alone.Thesimilar results were observed with CI.However,when variousconcentrations of histamine were incubated with cells for20min before adding anti-IgE or CI,the quantity of tryptasereleased was similar to that was induced by histamine alone.CONCLUSION:Histamine is a potent activator of humancolon mast cells,which represents a novel and pivotal self-amplification mechanism of mast cell degranulation. AIM: To investigate the ability of histamine to modulatetryptase release from human colon mast cells and the potential mechanisms. METHODS: Enzymatically dispersed cells from human colon were challenged with histamine, anti-IgE or calcium ionophore A23187 (CI), and the cell supernatants afterchallenge were collected. Tryptase release was determined with a sandwich ELISA procedure .RESULTS: Histamine at concentrations from 1 ng / mL was able to induce a “bell” shape dose related release of tryptasefrom colon mast cells. The maximum release of tryptase wasapproximately 3.5 fold more than spontaneous release. Aslittle as 10 ng / mL histamine showed a similar potency to 10 μg / mL anti-IgE in induction of tryptase release. Histamine induced release of tryptase was added at 10s when histamine (100 ng / mL) was added to cells, incremental increased after, and completed at 5 min. ormetabolic inhibitors were able to inhibit histamine inducedtryptase release. What histamine and anti-IgE were addedto colon mast cells at the same time, the quantity of tryptasereleased was similar to that induced by anti-IgE alone. Similar results were observed with CI.However, when variousconcentrations of histamine were incubated with cells for20min before adding anti-IgE or CI, the quantity of tryptasereleased was similar to that was induced by histamine alone. CONCLUSION: Histamine is a potent activator of human colony mast cells, which represents a novel and pivotal self-amplification mechanism of mast cell degranulation.