Enzymes of Tuberculous Exudates

In a former publication 2 we have shown that tuberculous tissue contains an enzyme which digests protein with considerable activity in the presence of an acid medium. This enzyme is present in the tubercle at all stages of its development and disappears only after caseation has occurred. During the formation of the lesion polynuclear leucocytes are abundant and for the first weeks after inoculation the newly formed tissue exhibits the enzymotic activity characteristic of these cells, namely, an ability to digest protein in the presence of an alkaline medium. At the end of about four weeks polynuclear leucocytes have in great part disappeared and the tissue has almost wholly lost its power to digest protein in the presence of alkali. Since the tissue at this time consists almost wholly of mononuclear epithelioid cells it may be assumed that they contain the enzyme which digests in an acid or in an approximately neutral medium but fails to digest in the presence of an alkaline medium. The cells of the tubercle are similar in appearance to the large mononuclear phagocytes of an inflammatory exudate and to the phagocytic cells which are abundant in the sinuses of lymphatic glands in the neighborhood of a focus of inflammation, and all these cells cause digestion of protein under the same conditions. The enzyme of such cells differs from the autolytic enzyme of various organs, for example of the liver, in its greater activity. 3 The demonstration of an active proteolytic enzyme in the epithelioid cells of the tubercle derives importance from the fact that these cells ingest and apparently dissolve tubercle bacilli and other