Stimulation of PBMCs with LCLs expressing HLA DR4 allotype rapidly expands TRAT-specific TRBV13⁺ CD8⁺ T cells. (A) PBMCs from HLA Cw*0602⁺ persons were stimulated with either HLA DRB1*0401⁺ LCL, T2.DR4, or T2.DR4/DM cells and then cultured for 7 days. After incubation these cells were assessed for expansion of TRAT-specific T cells (by the use of HLA-peptide tetramers) and IFN-γ expression by the use of ICS assays. PBMCs stimulated with DRB1*0401⁺ LCL or T2.DR4/DM cells showed strong expansion of TRAT-specific T cells. (B) T cells expanded after stimulation with T2.DR4/DM were costained with HLA-peptide tetramers and anti-TRBV13 antibodies. Representative data from 1 of the 3 unrelated donors are presented.