Alfred Nisonoff - Research Work

Research Work

Alfred Nisonoff was introduced to the subject of antibodies while studying at the Roswell Park Memorial Institute in Buffalo with a man named David Pressman. David Pressman was working in one of Linus Pauling’s groups exploring the antigenic specificity of antibodies against haptenic determinants. This research took advantage of the technique of quantitative hapten inhibition, originally developed by Karl Landsteiner. While conducting these experiments in Pressman’s lab, Nisonoff contributed to an important paper explaining an idea that eventually led to important conclusions about the structure of the antibody molecule. In this early paper he demonstrated that the antibody molecule has two combining sites with the same specificity for an antigenic determinant. This helped to disprove the “instructional theories” of antibody formation.

Alfred Nisonoff’s most important work started when he began the enzymatic cleavage of rabbit antibodies to better determine the structure that contributed to their specificity in disease. He was continuing the work of Rodney Porter who had performed the enzymatic cleavage of antibodies with the enzyme papain. When Nisonoff used a different enzyme, pepsin, to digest the antibodies, he discovered that the enzymes cleave the proteins at different sites on opposite sides of the disulfide bridge connecting the two heavy chains of rabbit IgG. This led to the conclusion that papain cleaves on the amino-terminal side of the disulfide bond, and pepsin cleaves on the carboxyl-terminal side. Nisonoff’s work also contributed to the identification of the F(ab’)2 fragment of the antibody molecule, which is the single bivalent fragment that is produced after pepsin cleavage. Later, it was found that this fragment is responsible for antigen interaction and agglutination and precipitation reactions.

Nisonoff’s experiment led to many conclusions about the structure of the antibody. It was determined that the two antigen binding sites of the antibody are located opposite the Fc fragment, the part of the antibody responsible for binding to receptor cells. Through the further work of his colleagues, with the help of Nisonoff’s previous work, the full structure of the antibody molecule as well as its amino acid composition were determined.

Alfred Nisonoff’s work continued to concentrate on efforts to determine how the structure of the antibody reflects its function and specificity as an immunological tool. In 1975, Alfred Nisonoff, John Hopper, and Susan Spring published the monograph The Antibody Molecule. This piece reviewed the comprehensive information available at the time on the structure and function of the B-cell receptor.

Nisonoff focused the remainder of his career in a variety of positions within the immunology community, including work for the Department of Biological Chemistry in Chicago and the National Institutes of Health (NIH). The research work of Alfred Nisonoff in determining the structure and functions of small proteins called antibodies, made major steps towards our modern understanding of the immune system. Without his work we may still be years behind our current understanding of the antibody molecule. Alfred Nisonoff died on March 12, 2001.