Maurice L. Cohn

Environmental effects on experimental aerogenic tuberculosis in BCG-immunized and non-immunized guinea pigs.

Summary BCG immunization confers immunity to guinea pigs under cold or high-altitude stress. Cold-exposed BCG-immunized animals had lower levels of immunity than controls, whereas those at high altitude were not significantly different from controls. Non-immunized animals at high altitude may be less susceptible to tuberculosis than those kept at −4°C. Moving boundary electrophoresis of serum samples showed an increase in the α 1-globulin of all animals 28 days post infection, and the α 1-globulin was greater in non-immunized than in immunized animals.

Chronic Aerogenic Tuberculosis in Mice

Summary Aerogenic tuberculous infection of mice with small numbers of tubercle bacilli resulted in chronic tuberculosis which persisted in some of the animals for over a year. The lesions produced by this infection contained a constant number (“steady state”) of culturable units of tubercle bacilli after 8 weeks, but there was enlargement and coalescence of the lesions because of an increased number of foam cell macrophages. In conse-sequence, there was an increased involvement of normal lung tissue. Thirty-six to 52 weeks after infection, the number of culturable units of tubercle bacilli had increased beyond that of the steady state; deaths continued to occur during this period.