Evolution of granulomas in lungs of mice infected aerogenically with Mycobacterium tuberculosis
Cardona, P.J.; Llatjós, R.; Gordillo, S.; Díaz, J.; Ojanguren, I.; Ariza, A.; Ausina, V.
Scandinavian Journal of Immunology 52(2): 156-163
2000
ISSN/ISBN: 0300-9475 PMID: 10931383 Document Number: 515602
Aerogenous infection of C57B1/6 mice with a virulent strain of Mycobacterium tuberculosis (CL 511) leads to the formation of primary granulomas in the lung where neutrophils, macrophages and subsequently, lymphocytes accumulate progressively around an initial cluster of infected macrophages. The spread of infection through the lung parenchyma gives rise to secondary granulomas featuring numerous lymphocytes that surround a small number of infected macrophages. Afterwards, foamy macrophages add an outer layer to the granulomas, which characteristically respect the pulmonary interstitium and remain confined within the alveolar spaces. This feature, in conjunction with the constant presence of M. tuberculosis in the products of broncho-alveolar lavage, suggests that the upward bronchial migration of infected macrophages may contribute significantly to pulmonary dissemination of mycobacterial infection. The latter would be in agreement with the persistence of chronic pulmonary infection in spite of a concomitant strong T helper 1 cell response.