Mast cells: Emerging sentinel innate immune cells with diverse role in immunity

Mast cells are phylogenetically old innate immune cells with less recognition in normal function of immune system as no such disease has been observed in humans due to their deficiency or inadequate function. Earlier mast cells were only known for their important role in the type 1 allergic reactions (i.e. anaphylaxis or some contact hypersensitivity reactions) due to release of various biochemical mediators (i.e. cytokines, chemokines, lipid mediators, proteases and biologic amines). Several studies indicated that they do not only come in action upon binding of IgE to its corresponding receptors expressed by them but also play an important role in host immunity. Recent development in understanding the mast cell biology has established various important roles of these cells in regulating both innate as well as adaptive immune response under normal or pathophysiological conditions (i.e. acute or chronic bacterial or parasitic infections, various autoimmune disease, pregnancy, etc.). Present review is designed to accommodate up to date information regarding mast cell development (i.e. factors governing mast cell development and their homing to various compartments (i.e. skin, lungs, intestine, uterus, etc.) along with their role in innate immunity, human pregnancy and future immunomodulatory approach comprising of targeting mast cells.