Immunology of T Cells in AIDS: Dynamics Revealed by Eight-Color Flow Cytometry

Individuals infected with the human immunodeficiency virus type 1 (HIV) suffer profound immunological changes. The loss of memory T cells leads to progressive immunodeficiency; the inability to replenish the naive compartment renders this immunodeficiency permanent. The limited immunity imparted by these cells may explain why there is only a limited set of opportunistic infections typically found in late-stage acquired immunodeficiency syndrome: other pathogens are sufficiently suppressed by the “unusual” T cell subsets. Understanding the basis for the changes in the T cells in HIV disease is crucial for the evaluation of potential therapies. In principle, the amount of antigen expressed on a cell surface will be proportional to the fluorescence obtained when cells are stained with a conjugated monoclonal antibody to that antigen. The loss of naive CD8 T cells predicates that the memory CD8 compartment is expanding—since total CD8 counts are elevated and remain relatively stable during most of the disease.