0.1 mL human whole blood cells were surface stained with 0.125 ug FITC-anti-human CD3 (FITC-65151, clone UCHT1) and 0.125 ug APC-anti-human CD4 (APC-65134, clone OKT4). Cells were then treated with red blood cell lysis buffer and were gated for lymphocytes for analysis of CD3 and CD4 staining. Cells were not fixed.