Figure 1. The endogenous processing of an immunodominant Gag epitope is more efficient than that of subdominant epitopes.

(A) HLA-A3 HeLa cells were pulsed with decreasing amounts of p17 Gag immunodominant RK9 (squares) or p17 Gag subdominant KK9 (triangles) and used as targets in a ⁵¹Cr release assay with RK9- or KK9-specific CTLs respectively. (B) HLA-A3 HeLa cells transfected with a CMV-driven HIV-1 LAV p17 expression vector (schemed above the graph) were used as targets in a ⁵¹Cr assay with RK9- (black bars) or KK9-specific (gray bars) CTLs. The recognition of endogenously processed RK9 and KK9 epitopes by specific CTLs (left side) was compared with that of transfected cells pulsed with 0.1 μM RK9 or KK9 peptides (right side). (C) p17 immunodominant RK9 (squares) and RT subdominant ATK9 (circles) peptide titration on HeLa-A3 cells. (D) HLA-A3 HeLa cells transfected with a CMV-driven vector expressing a HIV-1 LAV RT fragment (HXB2 residues 153–560) with a C terminal p17 sequence (5-RK9-3; according to the position of RK9) (schemed above the graph) were used as targets in a ⁵¹Cr assay with RK9- (black bars) or ATK9-specific (gray bars) CTLs. The recognition of endogenously processed RK9 and ATK9 epitopes by specific CTLs (left side) was compared with that of transfected cells pulsed with 0.1 μM RK9 or ATK9 peptides (right side). Lysis of cells without peptides or with mismatched peptides was below 3%. All data represent averages of 3 experiments.