Horse antisera, antibodies from

Emil Adolf von Behring (1854-1917) was a German microbiologist who discovered that diseases such as tetanus and diphtheria are produced not by the bacteria but by toxins produced by the bacteria, which circulate in the blood. He showed that immunisation with the toxin was sufficient to protect against the disease. He treated children with diphtheria by injecting serum from a horse immunised with diphtheria toxin. He recognised that the protective effect was due to substances circulating in the blood, from which he coined the term antibody. He was awarded the Nobel Prize in 1901 for the development of the diphtheria antiserum. 

Fig. 8. The same antigen solution (horse serum albumin) was placed in the upper layer of these two simple diffusion tubes. The antiserum used in the right-hand tube was that of the left-hand tube (i.e., anti-horse serum albumin) that had been partially absorbed by the homologous antigen, so that not only the antibody concentration had been decreased, but the proportion of precipitating to nonprecipitating antibodies had also been greatly decreased hence the difference in the appeiu-ance of the precipitation zone smaller density and fuzzy (instead of sharp) leading edge. The antiserum in the left-hand tube had been diluted in normal rabbit serum in order to ensure a similar penetration h in the two tubes. From J. Oudin, in Methods in Immunology and Immunochemistry (C. A. Williams and M. W. Chase, eds.), Vol. 3, p. 125. Academic Press, New York, 1971.

Precipitation of the antigen bound to antibody by using a second antibody. If, for example, the primary antibody is obtained from sheep, the second antibody can be antiserum raised against sheep immunoglobulins using a different animal such as a horse. 

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