Abstract
The results of recent studies of complement fixation in tuberculosis suggest that the test might be of considerable diagnostic value if satisfactory antigens could be prepared.
Three strains of tubercle bacilli were selected: one a virulent, another a non-virulent, human strain and a third bovine strain. Immune serum sufficient for titration with all the antigens was obtained from inoculated horses.
The antigens were prepared from cultures by various methods of fractioning and extraction similar to those used by other observers. The culture filtrates were so anticomplementary that they could rarely be used. The glycerine and distilled water extracts gave the most active antigens. These active antigens and also the culture filtrates for comparison were selected for further study by methods of adsorption.
Animal charcoal and globulin (horse serum) were used to adsorb the substances possessing antigenic action from the filtrates. When animal charcoal was added, the antigenic properties were removed, and could not be recovered by extraction of the charcoal. The adsorption with globulin was a more complicated procedure. The technique was briefly as follows: The original antigen was dialyzed and horse serum, one part to twenty of antigen, was added and allowed to stand in the incubator half an hour. The globulin was then precipitated by passing purified CO2 gas free from HCl through the mixture for one half an hour at 37° C. The globulin precipitate was collected and by shaking it with alcohol the antigenic substances were extracted. The alcoholic extract was concentrated in a vacuum.
The preliminary dialysis of the culture filtrate eliminated practically all of its anticomplementary action. The adsorption with globulin removed the antigenic substances from the culture filtrates and the aqueous extractions so that they were easily obtained in greatly purified and concentrated form.
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