[Histological and immunohistochemical structure of pulmonary tuberculotic granulomas in untreated cases and cases treated with antitubercular drugs].

INTRODUCTION

The changes occurring in response to antituberculotic treatment and immune defence were studied in human tuberculotic granulomas.

AIMS

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.

METHOD

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.

RESULTS

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.

CONCLUSIONS

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.