The Osler slide, a demonstration of phagocytosis from 1876: Reports of phagocytosis before Metchnikoff’s 1880 paper

Recently at the Medical Historical Museum of McGill University, Dr. Rick Fraser discovered a microscope slide prepared in 1876 from the lung of a patient with pneumoconiosis. Photomicrographs show the presence of coal dust particles in alveolar cells. This case and several related ones had been reported in 1875 by William Osler, who also had demonstrated the cellular uptake of carbon particles in kittens injected with India ink. In 1869 a Philadelphia physician described the uptake of bacteria by leukocytes in saliva and urine. Both investigators postulated a protective role for this cellular phenomenon. Neither of these reports has been generally cited in histories of immunology. These two papers are summarized here along with a short review of other reports describing phagocytosis which predating Metchnikoff’s entrance into the field.