Express Cell Surface Antibodies (Guava Technologies, Inc.) identify subsets of hematopoetic-derived cells by their patterns of protein expression. The antibodies allow examination of very specific population of hematopoetic-derived (blood) cell lines for their functional responses to compounds or other treatments. These antibodies have been conveniently optimized for ease of use with the Guava EasyCyte and EasyCyte Mini cell analysis systems. These new reagents allow the analysis of functional responses of one cell type in a mixed population of cells, such as whole blood, and can be used for automated sampling in 96-well plates. The products are direct conjugates to one of three different fluorescent dyes, eliminating the need for secondary staining and wash steps in the staining protocol. The antibodies are available in concentrations that eliminate extra dilution steps associated with other antibodies.