Enhanced Separation and Counting of CD4+ T Lymphocytes from Whole Blood Using a Quartz Microfluidic Magnetic Immunoassay

The ability to economically monitor the progression of the Human Immunodeficiency Virus (HIV) infections in patients living in resourcelimited areas is of critical importance to enhance the level of care received by patients. This is particularly important because careful monitoring of T lymphocytes subsets is one of the primary measures used in determining at which point to initiate antiretroviral therapy. This information is crucial to HIV infected patients because it allows for their care providers to adjust their treatment options based on their response to treatment. In this paper, we discuss the development of a re-useable quartz microfluidic device that was designed and tested to enhance point-of-care blood analysis and offers a method for rapidly determining absolute CD4+ T lymphocytes cell counts from whole blood. Blood was first diluted 10:1 in Hepes buffer solution, mixed with the magnetic bead solution and then introduced to the microfluidic device for continuous, magnetic separation by Magnetic Field Flow Fractionation. The device used commercially available magnetic beads that are functionalized with CD4+ antibodies to bind to the Cluster of differentiation 4 (CD4+) glycoprotein on T lymphocytes isolated from whole human blood. The CD4+ cell counts were obtained using an inverted optical microscope. The traditional CD4+ T lymphocyte counts were determined using a hemocytometer, after the cells were separated from whole human blood. The data shows an inverse relationship between capture efficiencies and flow rates while linear correlation was seen between capture efficiencies and the start cell densities. This microfluidic device seems well suited for use as a point-of-care device for determining absolute counts for CD4+ T lymphocytes in resource-limited areas.