CD38 on peripheral blood cells: The value of measuring CD38 expression on CD8 T-cells in patients receiving highly active anti-retroviral therapy

Abstract As in other viral infections, human immunodeficiency virus type 1 (HIV-1) induces an immune response, which translates into an increased lymphoid activation, despite CD4+ T-cell depletion. Such activation of the immune system is reflected not only by increased production of cytokines and other soluble factors, but also by modulation of the expression of T-cell activation-associated antigens, such as CD38, usually increasing their levels on the cell membrane. Since the first report showing that CD38 levels on CD8+ PB T-cells increase in subjects infected with the HIV-1, several studies have shown that such increased CD38 expression is a strong predictive marker for disease progression in HIV-1 infection. The levels of CD8+CD38+ T-cells not only predict progression of HIV-1 disease toward acquired immunodeficiency syndrome (AIDS) and death, but also offer additional independent predictive value to that of CD4 counts. In recent years, the introduction of highly active anti-retroviral therapy (HAART) has led to the suppression of HIV-1 replication with a dramatic decrease in plasma viral load levels in many HIV-1 infected subjects. However, success of HAART-based treatment is not achieved in all patients. Therefore, a need exists for adequate prognostic markers capable of predicting, in advance or in an early phase of treatment, lack of response to HAART. Also in this area, the measurement of CD8+CD38+ T-cells has been proposed as a useful tool for monitoring HIV-1 positive patients, given that an increased expression of CD38 on CD8+ PB T-cells could be an early marker of either viral replication or HAART failure.