CD38 expression on CD8 T cells has a weak association with CD4 T-cell recovery and is a poor marker of viral replication in HIV-1-infected patients on antiretroviral therapy.

OBJECTIVE: The aim of the study was to determine whether the expression of CD38 on CD8 T cells can identify patients with virological failure on antiretroviral therapy (ART).
DESIGN: This was a cross-sectional study of patients attending a single HIV clinic in London.
METHODS: The expression of CD38 on CD8 T cells was assessed using a biologically calibrated flow cytometry protocol. Patients were characterized by lymphocyte subset and viral load measurements. Characteristics including historical CD4 T cell counts, therapeutic history, co-infections and demographics were obtained from medical records.
RESULTS: Elevated levels of CD8 CD38(high) T cells were found in HIV-1-infected patients who failed to suppress viral replication with ART; however, this parameter lacked sufficient sensitivity and specificity to replace viral load testing in assessing the efficacy of ART. Increased levels of CD8 CD38(high) cells were associated with reduced CD4 T cell counts in HIV-1-infected patients on ART after correcting for known determinants of CD4 T-cell recovery.
CONCLUSIONS: The expression of CD38 on CD8 T cells lacks sufficient sensitivity and specificity to be used as a surrogate marker for viral load to monitor HIV-1 infection. T-cell activation is associated with reduced CD4 T-cell reconstitution in patients receiving ART.