The changes occurring in response to antituberculotic treatment and immune defence were studied in human tuberculotic granulomas.
To compare the possibilities of detection of Mycobacterium tuberculosis with the Ziehl-Neelsen staining technique and with an immunohistochemical method, and to assess the roles of lymphocytes and heat-shock protein 70.
40 patients who had undergone lung resection (the postoperative histology confirmed tuberculosis) were divided into two equal groups, on the basis of whether they had received antituberculotic treatment preoperatively (group I) or not (group II). Customary histology was used to determine the Langhans cells, epitheloid cells and lymphocytes, and an immunohistochemical method was then applied to examine the heat-shock protein 70 production of these cells and the normal lung. The lymphocytes were divided into CD4+ T-helper, CD8+ T-cytotoxic and CD20+ B cells by means of immune examinations. M. tuberculosis was demonstrated by an immunohistochemical method, with antibody against the wall protein.
Heat-shock protein 70 was produced by 17.6% of the Langhans cells and 94.4% of the epitheloid cells in group I, and by 100% of both cell types in group II. The bacterium could be detected in 40% of the total number of cases with acid-fast staining, and in 85% by immunohistochemistry. There was no significant difference in the qualitative distribution of the lymphocytes in the granulomas in groups I and II. The heat-shock protein 70 levels of the tuberculotic granuloma and the normal lung were significantly higher in group II.
The production of heat-shock protein 70 is more enhanced in untreated tuberculotic cases. On the basis of their heat-shock protein 70 production, the authors assume that a majority of the Langhans cells have a resting protective function in medically treated cases. Independently of the stage of the infection and of the use or not of antituberculotic treatment, the number of lymphocytes participating in the immune defence is constant. By means of immunohistochemical examination of the wall protein of M. tuberculosis, the presence of the tuberculotic disease can be demonstrated with high reliability.
"Detection of mycobacterial antigens by immunohistochemistry (IHC) using polyclonal and monoclonal antibodies is an alternative to conventional acid-fast staining. A large number of different mycobacterial antigens including BCG, lipoarabinomannan [5,13-17] have been detected with varying results in tissues. These are all common mycobacterial antigens and thus cannot discriminate M. tuberculosis from non-tuberculous mycobacteria. "
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to evaluate the diagnostic potential of immunohistochemistry using an antibody to the secreted mycobacterial antigen MPT64, in abdominal and lymph node tuberculosis.
We used formalin-fixed histologically diagnosed abdominal tuberculosis (n = 33) and cervical tuberculous lymphadenitis (n = 120) biopsies. These were investigated using a combination of Ziehl-Neelsen method, culture, immunohistochemistry with an antibody to MPT64, a specific antigen for Mycobacterium tuberculosis complex organisms. Abdominal and cervical lymph node biopsies from non-mycobacterial diseases (n = 50) were similarly tested as negative controls. Immunohistochemistry with commercially available anti-BCG and nested PCR for IS6110 were done for comparison. Nested PCR was positive in 86.3% cases and the results of all the tests were compared using nested PCR as the gold standard.
In lymph node biopsies, immunohistochemistry with anti-MPT64 was positive in 96 (80%) cases and 4 (12.5%) controls and with anti-BCG 92 (76.6%), and 9 (28%) respectively. The results for cases and controls in abdominal biopsies were 25 (75.7%) and 2 (11.1%) for anti-MPT64 and 25 (75.7%) and 4 (22%) for anti-BCG. The overall sensitivity, specificity, positive and negative predictive values of immunohistochemistry with anti-MPT64 was 92%, 97%, 98%, and 85%, respectively while the corresponding values for anti-BCG were 88%, 85%, 92%, and 78%.
Immunohistochemistry using anti-MPT64 is a simple and sensitive technique for establishing an early and specific diagnosis of M. tuberculosis infection and one that can easily be incorporated into routine histopathology laboratories.
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