Abstract
A rapid and sensitive method for detecting low concentration of cancer cells or specific cytotoxic cells is proposed. In this method, two biomarkers of specific T cells are used for detection simultaneously. One biomarker is conjugated with magnetic beads to separate specific T cell from the mixed cells and the other biomarker, associated with quantum dots, is used by detection the emission of fluorescence. The different population of specific T cell can be quantified using the relationship between the QD fluorescence intensity and the cell frequency following the magnetic separation. Non-specific adsorption and cross-reaction of QD625–streptavidin on a T cell membrane are prevented. Additionally, when a total of 108 cells are mixed, neither B cells nor red blood cells interfere with the detection of T cells. Moreover, the total detection time is less than 15 min, even though the frequency of specific T cells is as low as 5x10-7. Furthermore, the CTLs specific to Epstein-Barr Virus (EBV) can be detected at low concentration by using QD625–streptavidin conjugated with MHC-tetramer specific to EBV and immuno-magnetic beads The numerous advantages of detecting specific cells at low concentration using the presented method include ease of preparation, low cost, fast detection, and high sensitivity. The proposed system can be adopted to detect circulating tumor cells in the early stages for diagnosis or prognosis.