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Category: Clinical Microbiology; Bacterial Pathogenesis
Early Pulmonary Lesions in Rabbits, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555815684/9781555813734_Chap09-1.gif /docserver/preview/fulltext/10.1128/9781555815684/9781555813734_Chap09-2.gifAbstract:
In rabbits, 1- to 7-day pulmonary tuberculous lesions produced by aerosols are difficult to find because the inhaled dose of tubercle bacilli cannot be made large enough. A large intravenous dose, however, readily produces many such tubercles. This chapter describes their characteristics and provides information on the activation and multiplication of macrophages within such lesions. To produce these early lesions, the author's group injected rabbits intravenously with 108 to 109 tubercle bacilli (BCG). The blood-borne macrophages that entered the developing tubercles became partly activated during the first day. These entering macrophages retained their ability to divide, i.e., incorporate [3H]thymidine ([3H]TdR), even though they had ingested tubercle bacilli. In contrast, fully activated macrophages within tuberculous lesions lose their ability to divide. Pulmonary alveolar macrophages did not seem to participate in early pulmonary lesions produced by the intravenous route, but accumulated in the surrounding alveolar spaces. However, even though these alveolar macrophages were highly activated, they retained their ability to divide.
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One-day pulmonary lesion produced by intravenously injected BCG. A small blood vessel (part of which is cut tangentially) is depicted with an embolus of tubercle bacilli in its center (arrow). Some of the macrophages in this lesion stain ++ for β-galactosidase. In the alveolar spaces (on the left) are six or seven (dividing) [3H]TdR-positive mononuclear cells (probably lymphocytes and young macrophages). In the lower right corner are three [3H]TdR-negative alveolar macrophages, identified by their large size and +++ staining for β-galactosidase. In vitro [3H]TdR, 5-bromo-4-chloro-3-indolyl-β-D-galactoside, carbol-fuchsin, and hematoxylin. Magnification, ×760. Reproduced with permission from reference 1.
Two-day pulmonary lesions produced by intravenously injected BCG. A few acid-fast tubercle bacilli (arrows) can be seen in their small necrotic centers. Mononuclear cells from the bloodstream surround the centers. The lesions contained bright-blue ++ β-galactosidase-positive macrophages, some of which were necrotic. In the alveolar areas outside the lesions are about a dozen young β-galactosidase-negative mononuclear cells showing [3H]TdR incorporation. In vitro [3H]TdR, 5-bromo-4-chloro-3-indolyl-β-D-galactoside, carbol-fuchsin, and hematoxylin. Magnification, ×520. Reproduced with permission from reference 1.
Three-day pulmonary lesions produced by intravenously injected BCG. (A) In the upper part of the photograph is a [3H]TdR-positive macrophage staining ++ for β-galactosidase containing over 10 bacilli (upper arrow). Below this cell is a [3H]TdR-negative, + β-galactosidase-positive macrophage containing four bacilli (lower arrow). A +++ β-galactosidase-positive macrophage with two bacilli is at the far right. The lowest “black” cell is probably a [3H]TdR-positive, β-galactosidase-negative lymphocyte. (B) A [3H]TdR-positive, + β-galactosidase-positive macrophage containing two bacilli is marked with an arrow. Two +++ β-galactosidase-positive ([3H]TdR-negative) macrophages are also present. [3H]TdR-positive mononuclear cells containing bacilli were rare and could be found with assurance only in early pulmonary lesions. In vitro [3H]TdR, 5-bromo-4-chloro-3-indolyl-β-D-galactoside, carbol-fuchsin, and hematoxylin. Magnification, ×720. Reproduced with permission from reference 1.
Six-day pulmonary lesion produced by intravenously injected BCG and stained for cytochrome oxidase (CO). In the center are epithelioid cells rich in CO. Surrounding them are young infiltrating macrophages, most of which are still poor in CO. At the periphery are numerous alveolar macrophages, rich in CO, that were apparently attracted to the site by chemotaxins released from the lesion. Some of the epithelioid cells in the center are already necrotic, but their CO activity is still present. 1,2,3,4-Tetrahydroquinoline and p-aminodiphenylamine; no counterstain. Magnification, ×180. Reproduced with permission from reference 1.
Ten-day pulmonary lesion produced by an intravenous injection of BCG. In the caseous center of the tubercle are disintegrating β-galactosidase-negative epithelioid cells containing more than 10 faintly staining tubercle bacilli. Around the center are still-viable young β-galactosidase-negative mononuclear cells, several of which show [3H]TdR incorporation. Alveolar macrophages, staining +++ and ++++ for β-galactosidase, have accumulated in the surrounding alveoli below the tubercle. These alveolar macrophages did not contain tubercle bacilli, but several had incorporated [3H]TdR (not clearly seen in this photograph). In vitro [3H]TdR, 5-bromo-4-chloro-3-indolyl-β-D-galactoside, carbol-fuchsin, and hematoxylin. Magnification, ×320. Reproduced with permission from reference 1.