Cellular Components of M. Tuberculosis Contributing to the Pathogenesis

Mycobacteria are rich in lipids. Phosphatide fractions can produce tubercle like cellular responses and caseation necrosis. Lipids are to some extent responsible for acid-fastness. Virulent strains of tubercle bacilli form microscopic "serpentine cords" in which acid-fast bacilli are arranged in parallel chains. Cord formation is correlated with virulence. A "cord factor" (trehalose-6,6'-dimycolate) has been extracted from virulent bacilli with petroleum ether. It inhibits migration of leukocytes, causes chronic granulomas, and can serve as an immunologic "adjuvant".

Each type of mycobacterium contains several proteins that elicit the tuberculin reaction. Proteins bound to a wax fraction can, upon injection, induce tuberculin sensitivity. They can also elicit the formation of a variety of antibodies.

Mycobacteria contain a variety of polysaccharides. They can induce the immediate type of hypersensitivity (clinically not relevant).

Heat Shock Proteins