Quantitative Studies on the Precipitin Reaction: Antibody Production in Rabbits Injected with an Azo Protein
Throughout the 1930s, Heidelberger and Kendall continued to provide chemical proof that antibodies were protein by measuring
the amount of nitrogen in precipitates from reactions between antibodies and protein or polysaccharide antigens. John R.
Marrack, a British immunologist, had been critical of this work, maintaining that Heidelberger assumed that the reaction had
reached equilibrium and that only two antigen-antibody complexes were being formed, when in fact there might have been more.
Heidelberger's response, documented in this article, was to use a purplish-red diazo dye that chemically attached to the
protein antigen used, here the protein egg albumin. Heidelberger and Kendall purified antibody-antigen precipitates produced
by the precipitin reaction then subtracted the quantity of colored nitrogen (derived from the egg albumin antigen) from the
total amount of nitrogen. The remainder was the amount of nitrogen contributed by the antibody. Because almost all proteins
contain nitrogen, Heidelberger and Kendall thus concluded that antibodies were proteins. Moreover, they had developed a technique
that for the first time allowed measurement of antibody nitrogen in units of absolute weight and, with it, of the amount of
Item is a photocopy.
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1933-08 (August 1933)
Kendall, Forrest E.
Soo Hoo, Check M.
Periodical: Heidelberger, Michael, Forrest E. Kendall, and Check M. Soo Hoo. "Quantitative Studies on the Precipitin Reaction: Antibody
Production in Rabbits Injected with an Azo Protein." Journal of Experimental Medicine 58, 2 (August 1933): 137-152. Article.
[Rockefeller Institute for Medical Research]
Reproduced from the Journal of Experimental Medicine, 1933, 58, 137-152 by copyright permission of the Rockefeller University
Medical Subject Headings (MeSH):
Antigens and Antibodies: Heidelberger and The Rise of Quantitative Immunochemistry, 1928-1954