Rapid production of quasi-stable antibody-phycoerythrin conjugates for use in flow cytometry

A simple system is described for producing quasi-stable complexes between biotinylated antibodies and fluorochrome-labeled streptavidin. Optimal complexes were produced by mixing biotinylated antibody and phycoerythrin-streptavidin together at a molar ratio of 1:1 for 2 min, followed by the addition of soluble biotin to halt oligomerization. These complexes, which are stable for at least 4 h, exhibit fluorescence with cell binding which approximates that observed with standard two-step labeling techniques. Equally important, multiple biotinylated antibodies complexed with different streptavidin-fluorochromes can be used simultaneously.