[Simultaneous analysis of lymphocyte markers using triple color markers].

The introduction in flow cytometry of the new reagent Streptavidin Duochrome allows the simultaneous three color analysis of biological samples. Streptavidin Duochrome is a phycoerythrin-Texas red fluorochrome complex conjugated to the protein streptavidin. This novel complex exploits the principle fluorescence energy transfer when this reagent is used with FITC, PE and biotin-conjugated monoclonal antibodies; three different emissions of fluorescence are possible simultaneously using an argon laser at 488 nm (FACScan Becton Dickinson). Using Paint-a-gate software which analyses samples and displays the three colors on a screen, antigen distribution on multiple cell populations is obtained. Single, double and triple labeled cells (up to seven combinations) are visualized and quantified quickly and easily. Using a panel of normal donors we have evaluated the following combinations: CD3/CD4/CD8 to visualize T lymphocytes and their subsets; CD3/CD19/CD16 to quantify quickly the T, B, NK populations; CD4/Leu8/Leu18 to analyse the helper subset and CD3/CD8/Leu7. Our purpose is to evaluate the importance of this new kind of analysis to study the heterogeneity of several lymphocytic populations.