Abstract
Prior observations on the cellular reactions to tuberculo-phosphatide are confirmed and compared with reactions induced by this material in tuberculous animals. In the latter the response is accelerated and augmented and simulates the Koch phenomenon. Tuberculo-protein produces no macroscopic reaction in normal animals. The microscopic reaction of neutrophiles and monocytes regresses in less than a week. The same material in tuberculous animals causes a response characterized by more or less hemorrhage and necrosis, tissue degeneration, and infiltration of neutrophiles and monocytes. Late in the reaction there may be a few epithelioid cells and foreign body giant cells. Preparations of tuberculo-phosphatide which contain no tubercle bacilli, or only a few, induce the typical cellular response but do not induce hypersensitiveness to tuberculin. Repeated intradermal skin-test injections of tuberculo-protein MA-100 in normal guinea pigs may be followed by a mild hypersensitiveness to subsequent injections.