Follicular involution in HIV lymphadenopathy. A morphometric study.

Lymph node biopsies from 75 HIV infected patients (71 homo- and bisexual men, 3 hemophiliacs and 1 woman) were studied using immunohistochemical methods with monoclonal antibodies (Mabs) against B lymphocytes, subsets of T lymphocytes, follicular dendritic cells (FDC) and HIV gag proteins p24 and p18. Histopathological changes were classified as follicular hyperplasia (FH), fragmentation (FF), atrophy (FA) and depletion (FD). Immunohistochemical stainings were quantified with the help of an Image Quantifier (IQ) and the reactivity for respective Mab-defined antigen was related quantitatively to other antigens and histopathological changes. Such measurements showed an increase in FDC in biopsies with FH and FF histology and a decrease in FA and FD cases in comparison with cases with non-HIV related lymphadenopathy. In addition it was found that the decrease in FDC was correlated with an increase in CD8+ within the follicles. Double immunostainings for p24 and various cellular markers showed that p24 was predominantly associated with follicular dendritic cells. Essentially the same findings were observed in the lymph nodes irrespective of risk group. Possible mechanisms involved in follicular involution in HIV-related lymphadenopathy are discussed.