Isolation, characterization, and specificity of a glycoprotein antigen from Mycobacterium kansasii

We have isolated in highly purified form and characterized a glycoprotein antigen from culture filtrates of Mycobacterium kansasii. Immunoelectrophoretic studies demonstrated that this antigen is present only in M. kansasii among 14 species of mycobacteria studied. It is a potent tuberculin skin test antigen, but skin test reactions to it in sensitized guinea pigs display only limited specificity. Enzyme-linked immunoabsorbent antibody assays of serum samples from patients suffering from diseases caused by M. kansasii, M. intracellulare, and M. tuberculosis display no specificity with this antigen. These findings are best explained by hypothesizing a single highly antigenic determinant that is present as a moiety on many mycobacterial antigens and is widely shared among mycobacteria.