Development of a Microfluidic Device for CD4 T Cell Isolation and Automated Enumeration from Whole Blood.

The development of point-of-care, cost-effective, and easy-to-use assays for the accurate counting of CD4 T cells remains an important focus for HIV-1 disease management. The CD4 T cell count provides an indication regarding the overall success of HIV-1 treatments. The CD4 T count information is equally important for both resource-constrained regions and areas with extensive resources. Hospitals and other allied facilities may be overwhelmed by epidemics or other disasters. An assay for a physician's office or other home-based setting is becoming increasingly popular. We have developed a technology for the rapid quantification of CD4 T cells. A double antibody selection process, utilizing anti-CD4 and anti-CD3 antibodies, is tested and provides a high specificity. The assay utilizes a microfluidic chip coated with the anti-CD3 antibody, having an improved antibody avidity. As a result of enhanced binding, a higher flow rate can be applied that enables an improved channel washing to reduce non-specific bindings. A wide-field optical imaging system is also developed that provides the rapid quantification of cells. The designed optical setup is portable and low-cost. An ImageJ-based program is developed for the automatic counting of CD4 T cells. We have successfully isolated and counted CD4 T cells with high specificity and efficiency greater than 90%.