ANALYSIS OF THE LOCAL KINETICS AND LOCALIZATION OF INTERLEUKIN-1-ALPHA, TUMOR-NECROSIS-FACTOR-ALPHA AND TRANSFORMING GROWTH-FACTOR-BETA, DURING THE COURSE OF EXPERIMENTAL PULMONARY TUBERCULOSIS

A mouse model of pulmonary tuberculosis induced by the intratracheal i nstillation of live and virulent mycobacteria strain H37-Rv was used t o examine the relationship of the histopathological findings with the local kinetics production and cellular distribution of tumour necrosis factor-alpha (TNF-alpha), interleukin-1 alpha (IL-1 alpha) and transf orming growth factor-beta (TGF-beta). The histopathological and immuno logical studies showed two phases of the disease: acute or early and c hronic or advanced. The acute phase was characterized by inflammatory infiltrate in the alveolar-capillary interstitium, blood vessels and b ronchial wall with formation of granulomas. During this acute phase, w hich lasted from 1 to 28 days, high percentages of TNF-alpha and IL-1 alpha immunostained activated macrophages were observed principally in the interstrium-intralveolar inflammatory infiltrate and in granuloma s. Electron microscopy studies of these cells, showed extensive rough endoplasmic reticulum, numerous lysosomes and occasional mycobacteria. Double labelling with colloid gold showed that TNF-alpha and IL-1 alp ha were present in the same cells, but were confined to separate vacuo les near the Golgi area, and mixed in larger vacuoles near to cell mem brane. The concentration of TNF-alpha and IL-1 alpha as well, as their respective mRNAs were elevated in the early phase, particularly at da y 3 when the bacillary count decreased. A second peak was seen at days 14 and 21-28 when granulomas appeared and evolved to full maturation. In contrast, TGF-beta production and numbers of immunoreactive cells were low in comparison with the advanced phase of the disease. The chr onic phase was characterized by histopathological changes indicative o f more severity (i.e. pneumonia, focal necrosis and extensive intersti tial fibrosis) with a decrease in the TNF-alpha and IL-1 alpha product ion that coincided with the highest level of TGF-beta. The bacillary c ounts were highest as the macrophages became large, vacuolated foamy c ells, and containing numerous bacilli with immunoreactivity to mycobac terial lipids and lipoarabinomannan (LAM). These macrophages displayed poor and scarce TNF-alpha and IL-1 alpha immunostaining but still str ong immunoreactivity to TGF-beta. These cytokine production kinetics a nd the spatial relationship between immunostained cells and lung lesio ns corroborate the important role of TNF-alpha and IL-1 alpha in the c onstitution of granulomas and immune protection during the early phase of the infection, and also suggest an important if not primary role f or TGF-beta in the immunopathogenesis of the advanced forms of pulmona ry tuberculosis.