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Updated: Jun 19, 2026

Determining the Reactivity and Titre of Serum using a Haemagglutination Assay
Published on: January 29, 2010
THE STABILITY OF BACTERIAL SUSPENSIONS : III. AGGLUTINATION IN THE PRESENCE OF PROTEINS, NORMAL SERUM, AND IMMUNE
1Laboratories of The Rockefeller Institute for Medical Research.
Abstract:
1. The addition of proteins or serum to suspensions of bacteria, (Bacillus typhosus or rabbit septicemia) at different pH widens the acid agglutination zone and shifts the isoelectric point to that of the added substance. 2. The amount of serum required to agglutinate is much less near the acid agglutination point of the organisms. 3. The addition of immune serum prevents the salt from decreasing the cohesive force between the organisms, and agglutination therefore is determined solely by the potential, provided excess immune body is present. Whenever the potential is decreased below 15 millivolts the suspension agglutinates.
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