The History of Immunology

Abstract

Immunology begins with Edward Jenner’s discovery that vaccination with cowpox protects against smallpox. That there was an immune response was confirmed by the observations of many scientists that the same disease did not return a second time to a recovered individual. With the recognition by Friedrich Henle that germs caused disease, and the isolation of infectious bacteria by his pupil Robert Koch, the stage was set to examine how an immune response was achieved. Modern immunology begins with the research of Metchnikoff, who discovered the phenomenon of phagocytosis in starfish and extrapolated it to macrophages in humans as cells that engulf infectious agents; this was the beginning of cellular immunology. Paul Ehrlich investigated the formation of antibodies recognized as later as proteins that destroyed infectious agents. However, an explanation of how antibodies were formed and selected was puzzling. Did the body have enough genes to code for every type of antibody, and did specific cells produce antibodies, or did each cell have the ability to produce antibodies to any challenging molecule? Following the work of Karl Landsteiner, Felix Haurowitz, Niels Jerne and others, the “clonal selection theory” was proposed by MacFarlane Burnett. This theory states that each B-cell produces one type of antibody, and once activated, it expands and produces memory cells. Meanwhile, work on cellular immunity and innate immunity recognized the role of various types of T-cells, dendritic cells and cytokines in the immune response. New classes of T-cells and cytokines are constantly being found, and there is an intricate connection between these three branches of the immune system.