Suitable for immunomicroscopy and 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 reagent required to stain 1 x 106 cells in flow cytometry is approximately 1.0 µg of antibody conjugate. Lesser amounts of reagent may be sufficient for staining.