title: Tuberculin antigens: the need for purification.
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000302:isolation & purification*; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D012882:Skin Tests; D014373:Tuberculin / Q000302:isolation & purification*
chemical_list: D000942:Antigens, Bacterial; D014373:Tuberculin