Representative histology images demonstrating leukocyte composition and necrosis in 923-infected mice.

[A] Large areas of pulmonary necrosis (arrowheads) developed in mice sham-vaccinated and infected with the 923 clinical strain, consisting of high numbers of degenerate neutrophils with destruction of adjacent airways (arrow). [B] Protection from progressive pulmonary pathology was afforded by BCG vaccination, with development of lymphocyte-rich lesions (arrows) and a complete absence of necrosis. [C] Neutrophil-dominated inflammation and necrosis in a mouse immunized with rBCG 422 (arrows). The degree of inflammation is less severe than in sham-immunized controls.