ALDEFLUOR™ Assay Buffer can be used when counterstaining ALDEFLUOR™-reacted cells with immunofluorescently-labeled antibodies. The buffer is necessary to maintain ALDEFLUOR™ reaction product inside the cell, allowing detection of the ALDH-bright population. While there is sufficient ALDEFLUOR™-buffer contained within the ALDEFLUOR™ kit, additional buffer may be required for certain immunolabeling procedures.