MINIMAL EFFECT OF ADVANCED AGING ON SUSCEPTIBILITY OF MICE TO INFECTION WITH MYCOBACTERIUM-TUBERCULOSIS

Young (3-month-old) and old (greater-than-or-equal-to 24-month-old) mice of a long-lived strain were compared in terms of their ability to resist infection with Mycobacterium tuberculosis. There was little overall difference in the ability of young and old mice to resist this infection. Mice in both age groups could control infection in their livers and spleens by a mechanism that was predominantly CD4+ T cell-mediated but not in their lungs. Again, old mice were almost as capable as young mice at being immunized by bacille Calmette-Guerin against a challenge infection with M. tuberculosis. The results argue against including M. tuberculosis among infectious agents to which mice become susceptible with advanced age.