[Immunohistochemical characterization of HIV-and non HIV-associated lymph node tuberculosis]

Cells of MPS and lymphatic system in lymph nodes from eighteen patients with culture proven tuberculous lymphadenitis were examined by histological and immunohistochemical technics. Ten patients suffered from symptomatic HIV-infection and eight patients were immunocompetent individuals without HIV serology. Characteristic granulomas with or without caseation were observed in the eight immunocompetent and the four HIV-infected patients with less marked lymphopenia of CD4 positive peripheral blood lymphocytes. In lymph nodes from the other HIV-infected patients with more severe depression of CD4 positive peripheral blood lymphocyte count no epitheloid cell formation was present. Instead of these cells foamy macrophages were found. The phenotype of macrophages underwent progressive changes parallel to decreasing numbers of CD4 positive peripheral blood lymphocytes. Foamy macrophages in mycobacterium avium-intracellulare infection may represent an end-stage phenotype. While many macrophages and lymphocytes expressed IL-2 receptors in cases with typical granulomas there was no such CD25 expression in cases without any epitheloid cell formation. Our results suggest that T-cell activation is necessary for epitheloid granuloma formation in human tuberculosis and preliminary in situ data support the assumption that in vivo the HIV-infection provokes an excess production of cytokines which in turn causes an exhaustion of the immune system and finally AIDS.