Cyto-Last(TM) Buffer is specially formulated for the storage of cytokine producing cells. When used, staining of intracellular and/or extracellular targets for flow cytometric analysis can be delayed for up to two weeks. Cells should be stored at 4C during this time. This unique buffer ensures cells maintain a background staining signal equal to that of freshly prepared cells, while also retaining high specific immunofluorescent staining against target antigens.