A Passive Hemagglutination Reaction for Psittacosis

Abstract

Tannic-acid-treated sheep erythrocytes were sensitized with a soluble antigen sedimented at 100,000 × G for 80 min from meningopneumonitis infected allantoic fluids. Agglutination of sensitized cells was demonstrated with antisera from 22 (70%) of 31 humans who had experienced infections with psittacosis one to five years previous to tests. Four (13%) of 29 supposedly normal human sera manifested hemagglutinins. Substances responsible for nonspecific hemagglutination by normal human sera were adsorbed from the antigen preparation with untanned sheep erythrocytes. Evidence was presented that the hemagglutination and complement-fixation reactions measured different antibodies. Hemagglutinating antibodies were adsorbed from rabbit antipsittacosis sera with meningopneumonitis sensitized cells and complement-fixing antibodies were not removed by this treatment. The sensitizing antigen was not associated with either complement-fixation activity or with the murine hemagglutinin.