The human mast cell: Functions in physiology and disease

Mast cells are multifunctional, tissue-dwelling cells capable of secreting a wide variety of mediators. They develop from bone marrow-derived progenit or cells, primed with stem cell factor (SCF), which mediates its actions by interacting with the SCF receptor or c-kit on the cell surface. Mast cells continue their maturation and differentiation in peripheral tissue, develo ping into two well described subsets of cells, MCT and MCTC cells, varying in content of tryptase and chymase as well as in immunobiology. Mast cells are activated by numerous stimuli, including antigen (acting via the high a ffinity IgE receptor, Fc epsilon RI), superoxides, complement proteins, neu ropeptides and lipoproteins resulting in activation and degranulation. Foll owing activation, these cells express mediators such as histamine, leukotri enes and prostanoids, as well as proteases, and many cytokines and chemokin es, pivotal to the genesis of an inflammatory response. Recent data suggest s that mast cells may play an active role in such diverse diseases as ather osclerosis, malignancy, asthma, pulmonary fibrosis and arthritis. Mast cell s directly interact with bacteria and appear to play a vital role in host d efense against pathogens. Drugs, such as glucocorticoids, cyclosporine and cromolyn have been demonstrated to have inhibitory effects on mast cell deg ranulation or mediator release.