Utilizing a quartz crystal microbalance for quantifying CD4+ T cell counts

Acquired immune deficiency syndrome (AIDS) is a world wide epidemic. Third world countries, especially in Africa, suffer the most from AIDS. The progression of HIV/AIDS is monitored by the change in blood concentration of CD4(+) T cells. However, the most common technology used to measure CD4(+) counts, flow cytometry, has a high cost of capital, and is incapable of measuring in remote villages. An alternative method of measurement must be developed to help properly treat the individuals most affected in resource poor areas. In this paper, by using a self-assembled monolayer, we were able to attach anti-CD4 antibodies to the surface of a gold coated quartz crystal for use in a quartz crystal microbalance (QCM). The antibody coated QCM crystal was able to quantify the amount of CD4(+) T cells in phosphate buffer solution (PBS). Furthermore, the functionalized crystal did not respond to CD4(+) T cell controls in identical conditions. With these results we propose that QCM technology can be used to quantify CD4(+) T cells in patients who are HIV positive.