The APC003 antibody reacts with both allophycocyanin (APC) alone and APC conjugated with antibody or streptavidin, as well as APC tandem dyes such as APC/Cy5.5 and APC/Cy7. When APC003 antibody is used in a three-step staining procedure or separation of APC-antibody labelled cells, it neither quenches APC fluorescence nor reacts with tested mouse and human cells. The APC003 antibody can be used for separation of APC-antibody labeled cells or as a secondary step to amplify APC conjugated primary antibody signals (i.e. biotinylated APC003 as secondary step, followed by Streptavidin-APC).