1883

Metchnikoff, in first formulation of active host defense, publishes Research on the Intracellular Digestion of Invertebrates, in which absorption of microbes was merely part of multiple activities of mesodermic wandering cells. In 1884, he published three more papers that lay down the cardinal pillars of his phagocytosis theory: 1) mesodermal amoeboid cells had a diverse purpose analogous to original intracellular digestive function, namely, to engulf and devour atrophied host tissue or invading microorganisms; 2) tissue and blood leukocytes were functionally equivalent; 3) host defense was based on successful containment of pathogen by phagocytes; 4) the inflammatory reaction revolved around this phagocyte-pathogen struggle (Tauber & Chernyak, 137-141). The theory was opposed by Koenigsberg microbiologist/pathologist Paul Baumgarten, for whom only the organism acting as a whole, not the activity of individual cells (intracellular digestion by leukocytes) could assume responsibility for an organism’s integrity (143) and who ignored Metchnikoff’s emphasis on the differentiation of mesodermal cells and how they assumed new functions in evolution: “Baumgarten totally ignored that issue and therefore failed to discern differences in the general properties of phagocytes from the specific phagocytic activity of freely mobile white cells” (144).