Phycoerythrin conjugated streptavidin is suitable for immunomicroscopy, flow cytometry or FACS analysis, as well as other antibody based fluorescent assays requiring extremely low background levels, absence of F(c) mediated binding, lot-to-lot consistency, high titer and specificity. The maximum amount of Streptavidin Phycoerythrin required to stain 1 x 10E6 cells in flow cytometry is approximately 1.0 µg of antibody conjugate. Lesser amounts of Streptavidin Phycoerythrin may be sufficient for staining. Optimal titers for other applications should be determined by the researcher. As a general guideline dilutions of 1:100 to 1:250 should be suitable for most applications.