Mast cells are known to be involved in hyper-sensitivity reactions such as asthma and allergic rhinitis, and may probably participate in fibrinolysis at the site of acute inflammation. Rat mast cells were purified with a modified coil planet centrifuge at an average purity of 97%. In electron microscopy, mast cells were tightly packed with dense granules, and microvilli and cytoplasmic folds were well preserved, suggesting that the separation caused little damages to the cells. Sensitized cells responded well to the antigenic stimuli and released about 60% of histamine. Mast cell lysate showed remarkable fibrinolytic activity when measured with fibrin plates (BfP, BSP) and also showed chymotrypsin -like amydolytic activity, for it released substantial amount of chromophore from S-2586, S-2288, S-2444 and S-2251, S-2238 as well.
Fractions showing fibrinolytic activity were separated with AGI-X2, DEAE Sephadex A-25 ion -exchange column, followed by heparin Sepharose CL6B affinity column chromatography according to the method reported by Schwartz, L. B. et al.
Some of the characteristics of the enzyme are discussed in comparison with the tryptase from human lung mast cells and chymase from rat peritoneal mast cells.
