TGF-β significantly reduces intracellular perforin levels in nontransduced or eGFP-transduced CTLs, whereas perforin release is unaffected by TGF-β in HATGF-βRII-Δcyt–transduced CTLs.

Ninety-six hours after the addition of TGF-β (5 ng/mL), nontransduced (A,D), eGFP-transduced (B,E), and HATGF-βRII-Δcyt–transduced CTLs (C,F) were stained for intracellular perforin by using PE-labeled antiperforin antibody and were detected by flow cytometry. (A-F) These panels show representative histograms for CTLs from one donor cultured without TGF-β (A-C) versus with TGF-β (D-F). (G) This panel shows mean perforin levels from 6 CTL lines with and without TGF-β.