The Discovery of Mast Cells: An Historical Note

Mast cells are present in all classes of Vertebrates and have emerged > 500 million years ago, long before the development of adaptive immunity. Mast cells were first identified by the Nobel Prize winner Paul Ehrlich in 1878, when he was still a medical student. Mast cells are localized at the junction point of the host and external environment at places of entry of antigens (gastrointestinal tract, skin, and respiratory epithelium). Mast cells have been recognized as crucial effectors in both innate and adaptive immune responses. Mast cells protect against bacteria, fungi, protozoa, and viruses through the release of proinflammatory and chemotactic mediators. There is evidence that mast cells exert relevant functions in tissue homeostasis, remodeling, repair, and fibrosis. Moreover, mast cells accumulate at sites of tumor growth in response to numerous chemoattractants and release a vast array of mediators, some of which have promoting and others inhibitory effects on malignancies.