Inhibition of pulmonary granuloma formation in mice by treatment with Mycobacterial protoplasm and immuno-suppressants and its relation to protection against aerosol infection with virulent Mycobacterium tuberculosis.

Because the pulmonary granuloma formation by mycobacterial cell walls (CW) is likely mediated by cellular immunity, the effect of specific antigens and various immunosuppressants on pulmonary granuloma formation and protection against virulent m. tuberculosis, strain H37Rv was investigated in mice immunized with oil-treated CW from BCG or M. Tuberculosis, strain Aoyama B. Results of desensitization experiments with specific antigens showed that multiple intravenous injections of BCG protoplasm inhibited the footpad delayed hypersensitivity, macrophage migration inhibitory activity of lung cells and pulmonary granuloma formation as well as the enhancement of resistance against aerosol challenge with M, tuberculosis, strain H37Rv. However, treatment with nonspecific immunosuppressants like con A, silica or carrageenan induced only abrogation of footpad delayed hypersensitivity but not prevention of pulmonary granuloma formation or resistance against aerosol challenge. These results suggest a close relationship between pulmonary granuloma formation and protection against H37Rv in mice immunized with oil-treated mycobacterial CW.