Development of a multiplex fully automated assay for rapid quantification of CD4+ T cells from whole blood

Abstract

The development of cost-effective and rapid assays for the accurate counting of CD4 cells has remained prime focus for disease management. The lack of such assays has severely affected people living in resource-limited disease prevalent areas. CD4 count information plays a vital role in the effective management of HIV disease. There is an unmet need to develop rapid, cost-effective, portable and user-friendly point-of-care (POC) disease diagnostic platform technology for CD4+ T cell counting. Here, we have developed a flow-free magnetic actuation platform that uses antibody-coated magnetic beads to efficiently capture CD4+ T cells from a 30 μL drop of whole blood. On-chip cell lysate electrical impedance spectroscopy has been utilized to quantify the isolated CD4 cells. The developed assay has a limit of detection of 25 cells per μL and provides accurate CD4 counts in the range of 25–800 cells per μL. The whole immunoassay along with the enumeration process is very rapid and provides CD4 quantification results within 5 min time frame. The assay does not require off-chip sample preparation steps and minimizes human involvement to a greater extent. The developed impedance-based immunoassay has potential to significantly improve the CD4 enumeration process especially for POC settings.