An integrated microfluidic system for counting of CD4+/CD8+ T lymphocytes

This study reports on an integrated microfluidic system capable of counting CD4(+)/CD8(+) T lymphocytes from a whole blood sample, which may be further applied for the rapid screening of the human immunodeficiency virus (HIV) infection. This system is composed of a sample incubation module for fluorescence-labeling of the target cells and a micro-fabricated flow cytometry module for cell counting. First, a pneumatically driven, vortex-type micro-mixer has been adopted for the fluorescence-labeling of CD4(+)/CD8(+) T lymphocytes from whole blood. After the labeling process, different laser-excited fluorescent signals are detected and are used for counting of CD4(+)/CD8(+) T lymphocytes as they pass through the detection region of the microflow cytometer. A concentration of 963 cells/mu l is counted for cultured CD4(+) T lymphocytes with a reference concentration of 1000 cells/mu l. The ratio of CD4(+)/CD8(+) T lymphocytes is then calculated. Experimental results show that the results from the microsystem are in agreement with the ones from large-scale flow cytometers. In addition, the entire diagnostic procedure, including the sample incubation and the cell counting, can be automatically performed within 35 min. Therefore, this may become a powerful tool for further biomedical applications, especially for fast screening of HIV infection.