Measurement of resistance to experimental tuberculosis in albino mice. The immune phase.

Enhanced resistance against experimental tuberculosis was acquired by albino mice after peritoneal vaccination with living BCG. Prolongation of life was used as a measure of resistance against massive intravenous challenge infection. The average degree of prolongation of life was found to be directly related to the size of the vaccinating dose. The ultimate numbers of BCG bacilli recovered from the animal's organs were also directly related to the quantity of vaccine initially administered. It appears therefore that the relative degree of antitubercular resistance achieved by immunized mice is closely related to the vaccinal population present in the animal's organs.