Cellular Reactions to Fractions Isolated from Tubercle Bacilli

The cellular reactions in tuberculosis form one of the striking features of the disease and it is important to note that they can be produced by the dead bacilli. In 1890, Maffucci (1) studied the effect of subcutaneous injections of dead organisms; he recorded the formation of abscesses and the subsequent death of the animals from marasmus. The next year, Koch (2), in the well-known article describing the socalled Koch phenomenon, tested the reaction to subcutaneous injections of dead, as well as living tubercle bacilli, in normal and tuberculous guinea pigs. In normal animals he also produced local abscesses with dead organisms. However, in 1890, Wyssokowitsch (3) had also studied the effects of dead tubercle bacilli, using both subcutaneous and intraperitoneal injections in rats. He found nodules of epithelioid cells and giant cells and infiltrations with neutrophilic leucocytes; that is, the production of tubercles. These observations were repeated and extended by Prudden and Hodenpyl (1891) (4) and by Prudden (1891) (5), and were then repeatedly confirmed (6-11). The fact that dead bacilli will produce the lesions of tuberculosis is of great significance and sets the disease apart from other infections. It demonstrates that, in the actual infection, dead bacilli, as well as living, may play a rale and gives an especial interest to the study of the tissue response to chemical fractions isolated from the organism. Proteins, carbohydrates, and lipoids all play a part in these reactions, but the lipoids alone produce tubercles. These substances have the power to stimulate the formation of the epitheloid cell and its multinuclear form, the Langhans giant cell, which together are the essent,ial structural units of the tubercle. While chemical analyses of the organisms give only the vaguest clues