Objective.

To study the expression of the activation markers human leukocyte antigen (HLA)-DR and CD38 antigen on CD8+ T-lymphocytes in HIV-infected subjects and HIV-negative controls.

Design.

Two-and three-colour flow-cytometric analysis.

Methods.

Fresh peripheral venous blood was obtained from 16 HIV-infected subjects, representing four different stages of HIV disease, and from six HIV-negative controls. Three-colour lymphocyte immunophenotyping was performed using peridinyl chlorophyll-A protein (PerCP)-conjugated anti-CD8 monoclonal antibody (MAb) in combination with anti-HLA-DR (phycoerythrin) and anti-CD38 (fluorescein isothiocyanate) MAb.

Results.

The relative percentage of the lymphocyte populations thus defined differed between HIV-negative and HIV-positive subjects and between HIV-infected subjects at different clinical stages of disease. Simultaneous expression of HLA-DR and CD38 within the CD8 T-lymphocyte compartment increased from 8% in controls to 49% in asymptomatic HIV-infected subjects (P< 0.005). Symptomatic patients differed from asymptomatic seropositives by a further increase in the HLA-DR+ CD38+ CD8 subset. In AIDS patients, the HLA-DR+ CD38− CD8 subset decreased (P< 0.05) and the HLA-DR-CD38+ CD8 subset increased (P< 0.05), compared with the other HIV disease stage patients.

Conclusion.

There is a stage-associated pattern of HLA-DR and CD38 expression on CD8 T-lymphocytes during HIV infection; specific phenotypic patterns may have functional correlates in the host response to the virus.