GP120 IS PRESENT ON THE PLASMA-MEMBRANE OF APOPTOTIC CD4 CELLS PREPARED FROM LYMPH-NODES OF HIV-1-INFECTED INDIVIDUALS - AN IMMUNOELECTRON MICROSCOPIC STUDY

Objective: To study whether free gp120 can be detected on the plasma m embranes of apoptotic CD4+ T lymphocytes in lymph nodes from HIV-posit ive patients. Methods: Lymph-node cell suspensions prepared from three HIV-positive patients were studied by pre-embedding, double-immunogol d-labeling to identify cell type, determine cell morphology, and detec t the presence of bound gp120 molecules. Cells were classified by thei r surface antigens as helper/inducer T lymphocytes (CD4+), cytotoxic/s uppressor T lymphocytes (CD8+), B cells (CD20+), and total lymphocytes [CD45+, leukocyte common antigen (LCA)+]. Results: gp120 colabeled wi th both apoptotic and normal CD4+ T lymphocytes and LCA+ cells, but no t with either apoptotic or normal CD8+ T lymphocytes or B cells. gp120 was more often identified on apoptotic than on normal CD4+ T lymphocy tes. The gp120 and CD45 label were often colocalized. HIV particles we re not identified to be associated with or budding from either normal or apoptotic lymphocytes. Conclusions: Free gp120 is found bound to CD 4+ T cells in lymph nodes of HIV-infected individuals and potentially mark them for premature death by apoptosis.