ACTIVATED CYTOTOXIC LYMPHOCYTES IN LYMPH-NODES FROM HUMAN-IMMUNODEFICIENCY-VIRUS (HIV) 1-INFECTED PATIENTS - A LIGHT AND ELECTRON-MICROSCOPIC STUDY

Persistent generalized lymphadenopathy often develops during HIV-infec tion. It is characterized by follicular hyperplasia which progresses o ver time to follicular involution and finally lymphocyte depletion. To determine whether activated cytotoxic T cells (CD8+) are present in t he hyperplastic germinal centres, light and electronmicroscopic immuno gold labelling with monoclonal antibodies were used to localize two cy totoxic molecules, perforin and TIA-1, Perforin and TIA-1-positive cel ls were detected in the follicles and paracortex of lymph nodes from H IV-infected patients, whereas labelling was seen only in cells of the paracortex in the hyperplastic lymph nodes from HIV-negative patients. Cytotoxic granules, staining positive for perforin and TIA-1, were id entified by transmission electronmicroscopy, often in proximity to fol licular dendritic cells within the hyperplastic germinal centres of on ly HIV-positive patients. These cytotoxic cells may play a role in the follicular dendritic cell loss and concomitant follicular involution that occur during the evolution of HIV disease.