Serological cross-reaction between lipids of Mycoplasma pneumoniae and Mycoplasma neurolyticum.

The complement-fixing activity of crude lipid extracts of 10 Mycoplasma species was compared with that of whole organism antigens employing immune rabbit serum. Five species (M. pneumoniae, M. neurolyticum, M. granularum, M. laidlawii, and M. fermentans) showed serological activity, whereas the remaining five species (M. canis, M. felis, M. gallisepticum, M. hyorhinis, and M. pulmonis) did not show significant activity in their lipid fractions. The lipid fractions of the five species which had serological activity in their lipid fractions showed three groups of serological specificity. M. pneumoniae cross-reacted with M. neurolyticum, M. granularum cross-reacted with M. laidlawii, and M. fermentans showed specific activity. Acute and convalescent sera from human pneumonia patients from whom M. pneumoniae had been isolated showed antibody increases which could be measured nearly as well by lipids of M. neurolyticum as by those of M. pneumoniae. Only a few human convalescent sera showed antibody measureable by lipids of M. granularum, M. pneumoniae did not cross-react with M. neurolyticum by other serological parameters such as growth inhibition on agar or double immunodiffusion, indicating that only the lipid antigens of these two species cross-react.