Mast cells originate from progenitor cells in the bone marrow, circulate as undifferentiated mononuclear cells in the peripheral circulation, and subsequently mature under local influences following migration into tissue. Mast cells are widely distributed throughout the body in both connective tissue and at mucosal surfaces, and it has been estimated that if all the mast cells in the body were assembled together, they might form an organ the size of the spleen. They form a heterogeneous population of cells with differences apparent in their development, mediator content, ultrastructure, and functionally in their ability to interact with their local environment [1]. It seems likely therefore that human mast cells have many diverse roles. Experimental observations support this hypothesis, implicating a role for mast cells not only in allergic diseases, but also many other diverse physiological, pathological, and immunological processes including tissue remodelling, wound repair, pathological fibrosis, arthritis, angiogenesis, and host reactions to neoplasia [2]. What has not been so