Mast cells

Abstract

Human mast cells (MCs) are classified into two phenotypes as to whether they contain the detectable levels of chymase in their granules. MCs having chymase at high levels (MC TC) can respond to substance P and C5a, whereas MCs lacking detectable chymase (MC T) can respond to platelet-activating factor. While these MC phenotypes can be maintained over weeks when cultured in the standard culture condition supplemented with SCF and IL-6, MC TC lose chymase when they are cultured in the presence of culture supernatant obtained from IL-13-stimulated airway epithelial cells. MCs trigger not only the immediate-type allergic reaction in an IgE-mediated manner but also the late-phase allergic response and chronic allergic inflammation. However, it is necessary to consider the relative role of MCs in the allergic or innate-type inflammation by understanding cytokines/chemokines produced by other immune cell types and epithelial-mesenchymal tissues. The expression of these cytokines is almost completely blocked when glucocorticoid and FK506 are added simultaneously into the reaction buffer for MC activation. It would be difficult to overwhelm this effect even if we could develop a new anti-MC drug.