The early history of phagocytosis

Publisher Summary This chapter traces the development in the understanding of phagocytosis. Phagocytosis has a broad and a narrow definition. The former encompasses the spectrum of activities undertaken by a class of cells of the hematopoietic system in animal physiology related to tissue remodeling, immunity and inflammation. The latter is the attribute of particle engulfment that unifies this class of otherwise very diverse cells. Ilya Metchnikoff carried phagocytosis from its narrow to its broad conception. Moreover, the force of Metchnikoff's theory concerning the role of phagocytes in immunity and inflammation and the charm of the story by which he came to develop his theory have been so influential as to create the widespread belief that he discovered the narrower definition too, the fundamental cellular activity of phagocytosis. Metchnikoff cited the observation of an increased phagocytosis by leukocytes of microorganisms in immunized animals as evidence for his theory. But here he was on sorer ground, since the role of immunization in phagocytosis was later shown to be indirect, and since his adversaries marshaled evidence that infectious diseases prevailed in instances where there was brisk phagocytosis. Interestingly, some found Metchnikoff's ideas about battles between microbes and purposeful phagocytes too anthropomorphic and attacked him on this ground.