Purified human mast cells and basophils release human elastase and cathepsin G by an IgE-mediated mechanism

Human lung mast cells and human peripheral basophils were purified and examined for their content of proteolytic enzymes similar to lung Hageman factor activator (LHFA) previously found to be released from chopped human lung by an IgE-mediated mechanism. It was found that both cell types contained elastase and cathepsin G-like enzymes, and that elastase appeared to be responsible for LHFA activity. The enzymes, as well as histamine, were released in a dose-dependent manner from these cells by anti-IgE antibody and by ionophore A 23187. It appears that stimulation by either anti-IgE or ionophore increases the amount of both enzymes extractable from these cells. The release of these proteases may explain some of the inflammation and observed defects in coagulation which occur as a result of anaphylaxis.