Clinical applications and availability of CD4+ T cell count testing in sub-Saharan Africa

The absolute CD4+ T cell count in adults and CD4+ T cell percentage of lymphocytes (CD4%) in pediatrics compliment clinical history and physical examination to inform decisions about initiating antiretroviral therapy (ART). In addition, these immunologic markers predict host susceptibility to specific opportunistic infections, selected drug toxicities, and mortality. These benefits argue strongly for the availability of CD4+ T cell testing capacity in all settings where HIV infection is treated. Several currently available flow cytometry-based devices, and novel CD4+ T cell enumeration techniques such as the panleucogating CD4 are especially suitable for resource-constrained settings. At this time, unfortunately, the landscape of HIV care in sub-Saharan Africa is a mosaic characterized by large areas where CD4+ T cell testing capacity is limited or unavailable, and small, but growing, pockets where the capacity exists. Routine HIV quantification is currently unaffordable and unsustainable in the great majority of the region; therefore, a reliance on CD4+ T cell testing is inevitable for now. To this end, correcting the disparities in CD4+ T cell testing capacity and defining the minimum laboratory requirements for the safe use of antiretroviral drugs through well-designed clinical studies are some of the most urgent priorities of the ongoing global scale-up of ART.