Purification of serologically active phosphoinositides of Mycobacterium tuberculosis.

Glycolipids extracted with pyridine from three strains of Mycobacterium tuberculosis were fractionated. Phosphatidyl inositol, two phosphatidyl inositol dimannosides (A and M), and two phosphatidyl inositol pentamannosides (G and K) were separated and purified by a combination of solvent fractionations and chromatography on silicic acid. In each of these lipids, palmitic and tuberculostearic acids accounted for more than 90% of the total fatty acids. Mole ratios of fatty acid to P were: for phosphatidyl inositol, 2; for G and M, 3; for A and K, 4. Certain mixtures of A or M with G fixed complement with human sera from cases of tuberculosis. Two serologically inactive dimannosides, each containing two fatty acid ester groups per atom of P, were also present.