Studies of a Carbohydrate-Lipoid Complex from the Human Strain Tubercle Bacillus H37 *

The systematic study of cellular reactions to purified chemical fractions of the tubercle bacillus was first demonstrated by Sabin and her co-workers.'5 16, 17, 18 These chemically purified derivatives were prepared by Anderson of Yale. The above studies have contributed greatly to our knowledge of the pathogenesis of tuberculosis. Throughout all of the above work, however, no one specific factor was isolated to which the so-called "virulence" of the bacillus can be attributed. There has likewise as yet been no chemical evidence forthcoming which has shed any light upon the chemical differentiation between virulent and avirulent strains. Sabin et al. have shown, however, that the lipoid substances have exceeded all others in their ability to act as stimulants and maturation factors in the life cycle of the epithelioid cells of the host. This cellular phenomenon was demonstrated repeatedly with the phosphatide fraction of the bacillus. Later it was found that phthioic acid, a new fatty acid isolated by Anderson from the phosphatide fraction, was by itself capable of stimulating monocytes and epithelioid cells resulting in the formation of the tuberculous tissue. Although much work has been done with the phosphatide fraction, there has been no evidence assigning the latter to any specific role in the immunological mechanism of the disease. A great deal of investigation has been devoted to the antigenic properties of the lipoids, including fats, compound lipoids such as the phosphatides,1 4 5 cerebrosides, and the derived lipoids; also those substances obtained from the simple and compound lipoids by hydrolysis, e. g., sterols and fatty acids. Recently, Gerstl and his co-workers,6 using mycolic acids derived from the waxes of human, bovine, and avian tubercle bacilli, and from the leprosy bacillus, demonstrated that these hydroxy acids are responsible for the presence and persistence of the necrotic lesions induced by the above bacilli, but are not related to the elective pathogenicity of these different strains. The latter observations would tend to corroborate the findings