Persistence of protein, carbohydrate and was components of tubercle bacilli in dermal BCG lesions

Dermal tuberculous lesions were produced in rabbits with Bacille Calmette Guèrin and biopsied on days 4, 14, 21, 35, and 56. Frozen sections prepared from the biopsy specimens were stained by the peroxidase-antiperoxidase immunocytochemical technique with antisera against whole tubercle bacilli and antisera against the protein B, polysaccharide I, and wax D fractions of tubercle bacilli. In the primary lesions, protein B was often undetectable at 21 days, and polysaccharide I was often undetectable at 35 days. Wax D disappeared more slowly than the other bacillary components evaluated, and some wax D was still found at 56 days (if the lesions had not completely healed). Antisera against intact tubercle bacilli produced results similar to those produced by antiserum against wax D. These studies suggest that the chronicity of tuberculous lesions is due, at least in part, to the persistence of the wax D-like component of tubercle bacilli.