Measurements of precipitating antidiphtheria antitoxic and antibacterial antibodies in human blood sera, carried out by this new technique, have demonstrated higher levels of both antibody types in healthy adult vaccinees than in normal subjects who had contacts with diphtheria patients. Convalescents after diphtheria develop elevated levels of antitoxic and antibacterial antibodies, these levels growing to reach the concentrations similar to those in healthy vaccinees.
