Edu-2 (CD4) / MCD8 (CD8) dual combination is a direct immunofluorescence reagent used for the detection of mature human T helper/inducer (CD4+) and suppressor/cytotoxic (CD8+) lymphocytes in whole blood (either lysed or non-lysed) using flow cytometry. Additionally, the T helper / suppressor ratio (CD4+/CD8+) may be determined.