Humoral Immunity - History

History

The concept of humoral immunity developed based on analysis of antibacterial activity of the components of serum. Hans Buchner is credited with the development of the humoral theory. In 1890 he described alexins, or “protective substances”, which exist in the serum and other bodily fluid and are capable of killing microorganisms. Alexins, later redefined "complement" by Paul Ehrlich, were shown to be the soluble components of the innate response that lead to a combination of cellular and humoral immunity, and bridged the features of innate and acquired immunity.

Following the 1888 discovery of diphtheria and tetanus, Emil von Behring and Kitasato Shibasaburō showed that disease need not be caused by microorganisms themselves. They discovered that cell-free filtrates were sufficient to cause disease. In 1890, filtrates of diphtheria (later named diphtheria toxins) were used to immunize animals in an attempt to demonstrate that immunized serum contained an antitoxin that could neutralize the activity of the toxin and could transfer immunity to non immune animals. In 1897, Paul Ehrlich showed that antibodies form against the plant toxins ricin and abrin, and proposed that these antibodies are responsible for immunity. Ehrlich, with his friend Emil von Behring, went on to develop the diphtheria antitoxin, which became the first major success of modern immunotherapy. The presence and specificity of compatibility antibodies became the major tool for standardizing the state of immunity and identifying the presence of previous infections.