Direct haemagglutination by Mycoplasma pneumoniae and its inhibition by immune serum.

Summary Direct haemagglutination of guinea-pig red cells by Mycoplasma pneumoniae has been demonstrated. Optimal haemagglutinin yields were obtained when the organisms were grown in shaker cultures, harvested on the day when the viable count was highest and concentrated ten-fold. Haemagglutination-inhibiting antibodies were demonstrated and quantitated in sera of immunised rabbits and of patients infected with M. pneumoniae.