Immune response to Mycobacterium tuberculosis in rats

After intravenous injection into rats, both the attenuated strain R1Rv and the virulent strain H37Rv of Mycobacterium tuberculosis grow in the liver and spleen. However, the infected rats mount a specific immune response with great rapidity, giving a false impression of natural resistance to the tubercle bacillus. Adoptive immunity to tuberculosis was achieved by transferring thoracic duct cells from immunized donors to normal syngeneic recipients. The transferred immunity was vested in a population of lymphocytes uncontaminated with macrophages. The adoptive immunity was effectively expressed against both attenuated and virulent tubercle bacilli, and it was shown to be immunologically specific. Lymphocytes which conferred immunity to tuberculosis were not protective against Listeria monocytogenes infection, and vice versa. Immunity could not be transferred with either normal thoracic duct lymphocytes (TDL), heat-killed sensitized TDL, or serum from specifically immunized donors. The ability of TDL from BCG-immunized donors to confer immunity was maintained at an unimpaired level for at least 3 months after immunization.