Hsp70 and Fas are exposed on K562, Tag7, and FasL are exposed on CTLs. Specified 6-day LAK subpopulations were isolated using antibody-coated magnetic beads. (A) Flow cytometry of Fas⁻ and Fas⁺ K562 for the presence of Hsp70 on their surface. (B) Biotinylated Tag7 isolated from surface-labeled FasL⁻ and FasL⁺ CTLs (streptavidin-peroxidase blotting). (C) Flow cytometry for Tag7 exposure on FasL⁻ and FasL⁺ LAKs. (D) Flow cytometry for Tag7 and FasL exposure on purified CD4⁺CD25⁺ cells. Top right quadrants (B2) contain double positives.