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Subject - Immunology
Mast cells play an important role in the non-specific defence of the immune system. These cells got their name because of their appearance under an optical microscope – in 1878, Paul Ehrlich erroneously supposed that mast cells could be phagocytic cells that have eaten their fill; but these cells actually produce the many vesicles they contain themselves. These vesicles contain heparin, as well as enzymes, leukotrienes, prostaglandins or cytokines, and the inflammatory mediator histamine, which is released upon activation of the mast cells (degranluation) and elicits the typical symptoms of an inflammation: expansion of the blood vessels and warming of the tissue.
Mast cells are also involved in IgE-mediated allergies such as asthma. The reaction cascade starts with antigen-specific IgE antibodies, which are secreted through exocytosis by plasma cells after first contact with the allergen and then circulate in the blood. These antibodies bind to the surfaces of mast cells. When there is renewed contact between this antigen and the mast cells, histamine is released from the vesicles and the instant allergic reaction is triggered.