A representative dot plot of ICOS staining in a melanoma patient at baseline and after anti-CTLA-4 therapy, as well as the mouse IgG1 isotype control (A). All samples analyzed for % CD4+ICOShi expression in the different donor and patient groups at different time points (B) (HD, healthy donor; Mel-Pt, control melanoma patients; Pre-tx, pre-treatment; SAV, streptavidin).