Studies on tubercle bacillus-monocyte relationship. III. Conditions affecting the action of serum and cells; modification of bacilli in an immune system

Studies of the relationship of protective serum factor to cellular resistance and to tuberculin skin sensitivity have demonstrated that protective serum factor may exist independently of a high level of cellular resistance, and that both protective factor and cellular resistance may be demonstrable without a concomitant hypersensitivity of the delayed type. The experiments with absorbed sera and the globulin fraction of immune serum indicated no specific association of protective serum factor with antibody globulin. The protective factor in immune serum was found to be thermostable and non-dialyzable. In vitro exposure of virulent tubercle bacilli to the immune serum from BCG-immunized animals failed to alter the bacterial capacity for destruction of monocytes and for intracellular proliferation. In vitro cultivation of normal and immune monocytes in normal or immune serum was not effective in changing the native susceptibility or resistance of these cells. Effective manifestation of resistance to virulent tubercle bacilli by immune monocytes was found to require the continuous presence of immune serum. The intracellular passage of virulent tubercle bacilli in an immune system (immune monocytes cultivated in immune serum) resulted in a decreased bacterial potential for destruction of normal monocytes when these were cultivated in the presence of immune serum.

The specificity of the passive hemagglutination methods used in serology of tuberculosis

The Middlebrook-Dubos hemagglutination test with normal red cells and the Boyden hemagglutination test with red cells tanned with tannic acid were shown to be strictly specific, for tubercle polysaccharide and for the protein antigens. The former test detects polysaccharide antibodies and the latter protein antibodies. Convincing evidence is given that polysaccharide does not adhere to the surface of tanned red cells nor protein to the normal red cell surface. Hemosensitizing ability and in vitro antigenicity were found to be two distinct properties of tubercle polysaccharide and protein antigens. The phosphatide hemagglutination test with normal red cells sensitized with tubercle phosphatide is also specific; it detects only phosphatide antibodies. The three different kinds of antibodies, antipolysaccharide, antiprotein, and antiphosphatide, were shown to be completely distinct from each other in tuberculous serum. Each of them can be completely removed from serum by absorption with red cells or kaolin particles coated with its corresponding antigen. The reliability of the cross-inhibition test is discussed.

Studies on fractions of methanol extracts of tubercle bacilli. II. Toxic and allergenic properties of fractions employed as antituberculous vaccine

Fractions of methanol extract which had been previously demonstrated to increase the resistance of mice to experimental tuberculosis have been subjected to an examination of their toxic and allergenic properties. The criteria for toxicity were: (a) production of inflammatory skin reactions in guinea pigs; (b) induction of weight loss in mice by intraperitoneal injection; and (c) depression of resistance to staphylococcus infections in mice. Allergenicity of a preparation was investigated by (a) its ability to evoke a hypersensitive skin response in guinea pigs previously sensitized with whole tubercle bacilli; and (b) its capacity to induce hypersensitivity to one or more of its components when injected under appropriate conditions into guinea pigs. Fraction F I, a preparation precipitated from methanol extract by slow concentration at 45°C., was found to possess some toxicity and some allergenicity by all of the criteria employed. Subfraction F I-P, precipitated from aqueous suspensions of F I by 33 per cent ethanol and 0.5 per cent NaCl, was apparently the F I component responsible for these activities. The saline-ethanol-soluble subfraction, F I-S, was neither toxic nor allergenic by the tests performed. These findings were considered of particular interest inasmuch as F I-S, despite its small yield, had been shown earlier to be the most active single substance used as vaccine to increase resistance to experimental tuberculosis in mice.

Studies on tubercle bacillus-histiocyte relationship. V. Passive transfer of cellular resistance

Studies of passive transfer of cellular resistance, as manifested by refractoriness to necrotization with virulent tubercle bacilli, have shown that immune histiocytes or immune lymphocytes were effective transferring agents; immune polymorphonuclear leucocytes and immune serum as well as comparable cells from normal animals lacked this capacity. Comparisons of immune histiocytes and immune lymphocytes showed that the former cells were more efficient; this was indicated by (a) the smaller numbers of immune histiocytes needed for passive transfer, (b) the longer duration of cellular resistance in recipients given histiocytes than in those given lymphocytes, (c) the greater capacity of histiocytes to effect serial passive transfer, and (d) the ability of histiocytic but not lymphocytic lysates to transfer cellular resistance. Experiments to establish the mechanism of passive transfer of cellular resistance showed that there was no active induction of resistance in recipients through transfer of bacillary antigens contained in immune histiocytes; in fact, the results of serial passive transfers with immune histiocytes suggested an active replication of the "cell resistance factor."