Activation and expansion of tumor antigen-specific T cells in PBLs, detectable ex vivo. PBLs from patient LAU 750 were analyzed by flow cytometry by ex vivo staining with HLA-A2/Melan-A multimers and CD45RA-specific mAbs. The numbers indicate the percentages of multimer positive cells that are CD45RA- (upper left quadrant) or CD45RA+ (upper right quadrant). The dot plots show CD8-sorted T cells (100% corresponds to the total number of CD8+ lymphocytes).