[Frontiers in Bioscience 3, c27-33, May 1, 1998] |
LURIEíS TUBERCLE-COUNT METHOD TO TEST TB VACCINE EFFICACY IN RABBITS
Departments of Environmental Health Sciences, Molecular Microbiology and Immunology, and Epidemiology, School of Hygiene and Public Health; and the Department of Pathology, School of Medicine, The Johns Hopkins University, Baltimore, Maryland 21205
Received 3/9/98 Accepted 3/14/98
4. RESISTANCE TO THE ESTABLISHMENT OF THE INFECTION
Clinical tuberculosis is prevented by two distinct host defense mechanisms: (a) resistance to the establishment of the infection and (b) resistance to its progress (1,9-11). The pulmonary alveolar macrophages (AM) prevent inhaled bacilli from establishing lesions. AM are highly activated cells, activated by the continuous ingestion and digestion of inhaled organic particles including microorganisms (12). In humans and rabbits inhaling virulent human-type tubercle bacilli, the AM usually kill most of the inhaled bacilli before they have had a chance to multiply appreciably. An early microscopic pulmonary lesion is established only when a strong bacillus is ingested by and multiplies within a weak alveolar macrophage (13,14). Once such a lesion is established, the host can use its broadly specific innate defenses (15,16) and its acquired immunologically-specific defenses to stop the lesionís progress and prevent grossly evident disease (see next section).