[Flow cytometric analysis of surface antigens on liquid nitrogen-stored cells]

A high non-specific fluorescence background imposes serious interference on a flow cytometer in surface antigen assay for those cells stored in liquid nitrogen. The non-specific fluorescence comes from dead and dying cells, the permeability of whose membrane has been increased so that the fluorescence reagent can enter into the cells. To solve this problem, liquid nitrogen-stored PBMNC and Raji cells were screened on different gatings for surface antigen stained with fluorescence. It was observed that the high fluorescence background as well as debris can be gated out by means of gating on FALS, angle 90 degrees angle and PRFL. As a result, the percentage of surface antigen positive cells determined was close to that assayed in fresh samples.