In situ immunophenotyping of lymphocytes/macrophages: grading of lymphadenopathy, staging and pathophysiology of HIV infection.

Histological changes in lymph nodes in HIV1-related lymphadenopathy were analysed in 106 lymph node biopsies and in lymph nodes of 140 autopsy cases. A classification system of five stages was established on the basis of histological and immunohistochemical studies. The analysis confirmed a close correlation between the progression of HIV1-related disease and our staging system. Although the classification is chiefly based on histological and immunohistochemical changes of the follicles, other frequently seen findings are included. Alterations in the interfollicular tissue, e.g. vascular proliferation and lymphocyte depletion, correspond to an increasing concentration of macrophages within this tissue. In HIV1 infection, the macrophages appear to produce high concentrations of angiogenic factors responsible for the frequent and sometimes extreme lymph node vascularization. Since the vascular proliferation can be subject to regression and sclerosis as seen in autopsy cases, the macrophages may lose the ability to produce large amounts of angiogenic factors in the final stage of the disease.