Dialyzable tuberculins: their abilities to participate in or inhibit immune reactions

Dialyzable components of culture filtrate of Mycobacterium bovis were fractionated by gel filtration on Sephadex G-10 into eight fractions, A through H in order of their elution from the column. None of the fractions produced a visible precipitate when reacted with a hyperimmune antiserum. The first five fractions were further investigated. All were capable of inhibiting precipitation of nondialyzable tuberculin. Fraction E, containing the smallest fragments, totally abolished precipitation and fraction A, which contained the largest molecules inhibited the least. Fractions A and B were the only ones that could induce skin reactions in sensitized guinea pigs but did this poorly. In vitro transformation of PPD sensitized lymphocytes was induced only by fraction A. Only fractions A and B could inhibit transformation of lymphocytes by Concanavalin A but only fraction B could inhibit transformation by tuberculin. Dialyzable components injected intracardially 3 hours prior to skin testing with tuberculin caused a reduction in skin reactivity. Since such substances are present in tissues in late stages of tuberculosis investigations were made to determine if they played a role in the induction of the observed accompanying tolerance to skin test cellular hypersensitivity. Guinea pigs treated with dialyzable components prior to and for four weeks post sensitization did not develop tolerance.