Abstract
The ability to rapidly identify immune cell subsets such as CD4 cells, which became possible around the same time as the onset of the HIV/AIDS pandemic, was one of the greatest advances in clinical and diagnostic immunology. The evolution of this global pandemic and the subsequent development of treatment strategies to prolong the life of infected individuals mean that it is now more crucial than ever that we develop affordable, reliable and accurate methods for the enumeration of CD4 cells. Here, we provide an overview of the historical developments in CD4 enumeration technologies that are related to HIV infection, and summarize the current technological challenges that must be overcome to meet the needs of those living with HIV infection.