Fig. 3.

The TAP-independent, Tapasin-independent peptide CLG is not presented in SCLC cells unless cells are pretreated with IFNγ. HLA-A*0201-positive SCLC cell lines a NCI-H69 and b NCI-H345, either untreated or pre-treated with IFNγ for 48 h, were infected with vTK-as a control or with a vaccinia–minigene recombinant expressing the TAP-independent, Tapasin-independent CLG peptide (vCLG). SCLC cells exposed to the antigenic peptide or to an equivalent concentration of DMSO solvent served as positive and negative controls. 2 × 10⁴ target cells per well were incubated overnight with CLG-specific CTL clone WT c20 at 3,000 cells per well. Results represent the mean values of IFNγ release measured from triplicate cultures (+SD) and are from one representative experiment out of three