Antigenicity of the phosphatidyl inositomannosides of mycobacteria

Purified di- and hexamannoside components ofMycobacterium 607 (M. 607) were analysed for their immunochemical relationships in agglutination and precipitation tests, using antisera against the MBSA complexes of total mannosides, M₂-3F^† and M₂-4F components of dimannosides. The agglutinating antibody to total mannosides seemed to be different from that given by the precipitation test. There was no cross-reactivity between PI and the mannoside antigens, which suggested the association of antigenicity with the mannose units of the mannosides. Dimannosides with 2, 3 and 4 esters showed complete cross-reactivity. However, different antigenic specificities were found to be associated with di- and hexamannoside antigens in the immunochemical reactions. The deacylated mannoside lacked serological reactivity with antiserum to the mannosides. However, the additional fatty acids in the inositol-oligomannosyl region of the dimannosides did not seem necessary for reactivity or specificity.