Figure 4. Tumor antigen specific secretion of IFN-γ and granzyme B by human CD8⁺ T cells is regulated by the extracellular arginine concentration, whereas perforin secretion is independent of arginine.

Expanded MART-1_{aa26–35*A27L} specific CD8⁺ T cells of 3 HD were activated with MART-1_{aa26–35*A27L} peptide (black bars) or control peptide (white bars) loaded T2 cells in medium with different concentrations of arginine (0, 5, 20, 150 and 1000 µM) in ELISPOT assays. After 24 h supernatants were harvested to determine granzyme B/perforin release by ELISA and IFN-γ was detected on ELISPOT membranes. A Results of ELISPOT assays are shown as mean of triplicates. The corresponding ELISPOT membranes of activation with MART-1_{aa26–35*A27L} peptide loaded T2 cells are shown below the diagrams. B Granzyme B/perforin concentration in supernatants of ELISPOT assays of 2 HD determined by ELISA.