65animals were injected into separate areas of the skin with 40 pg of cell walls and 40 pg of protoplasm of homologous organisms. At 48 hours postinjection, protoplasm had caused little reaction a t the site of inoculation, whereas cell walls had produced severe reaction in the 6 animals that had received an initial injection of cell walls. The lesions were red and edematous and varied from 20 x 7 to 38 x 35 mm in diameter. The 3 animals that had received protoplasm as the initial inoculum developed flat lesions varying from 7 x 7 to 13 x 13 mrn in diameter following the second inoculation of cell walls, although the 3 normal animals failed to respond. These results demonstrate that cell walls contain fractions capable of inducing hypersensitivity of the delayed type and of eliciting skin reactions in sensitized animals.Initial lesions produced by mycobacteria injected into the skin of rabbits do not appear until after 4 or 5 days. In this respect these organisms differ from B . tularense and Hemophilus pertussis suspensions which produce visible effects in rabbits within 24 hours( 1 0 ) . Initial and sensitivity reactions produced by fractions of mycobacteria can be differentiated by their time of appearance. Details of these and other studies will be discussed later.Summary. A technic was described for separation of cell wall and internal protoplasm from cells of Mycobacteria. Data are presented which demonstrated that cell walls produced lesions when injected intradermally into rabbits, whereas protoplasm failed to produce these lesions. Cell walls were also shown to be capable of inducing hypersensitivity of the delayed type. Separation of these morphological elements resulted in definite separation of one element possessing certain biological activities from material not possessing these characteristics. Such initial fractionation of the cell should facilitate purification and characterization of substances which elicit typical tissue responses to infection with tubercle bacilli.
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