In vitro and in vivo reactivity and specificity of fractions from sonicates of Mycobacterium tuberculosis separated by gradient acrylamide gel electrophoresis.

Fractions of cell sonicates from the H37Rv strain of Mycobacterium tuberculosis prepared by gradient acrylamide gel electrophoresis (GAGE) were examined by immunoelectrophoretic analysis and tested for biologic reactivity and antigenic specificity. Each was tested for the ability to elicit delayed type hypersensitivity reactions in the skin of guinea pigs sensitized with M. tuberculosis, M. kansasii, M. intracellulare (Battey), M. scrofulaceum (Gause), and M. fortuitum. Peripheral lymphocytes from persons infected with mycobacteria were also exposed to fractions, and the increase in [3H]thymidine incorporation into DNA was used as an index of stimulation (lymphocyte transformation). Only 4 fractions (6, 11, 12, and 16) were found to be significantly more specific than the unfractionated sonicate, and none was monospecific for M. tuberculosis. The results of fused rocket immunoelectrophoresis suggested that incomplete separation of antigens and/or shared group-specific multideterminant antigens may have accounted for the observed cross-reactions.