Phenotypic characterization of CD8_CXCR5+ICOS+T cells. Expression of various markers was analyzed by flow cytometry in CD8_CXCR5+ICOS+ cells compared with CD8_{CXCR5−ICOS−} and T_FH subsets (n = 5-6). Representative figures from 1 cHL case are shown for expression of chemokine receptor CCR7 (A), PD1 and BTLA coexpression (black) vs isotype control (gray) (B, top), transcription factor Bcl-6 and effector molecules like OX40, CD200 (B, bottom). (C) Percentage of cells positive for the activation marker HLA-DR and the proliferation marker Ki67. (D) Percentage of cells positive for perforin, granzyme B, and Eomes in each cell subset. Statistical analyses using the Mann-Whitney nonparametric U test between CD8_CXCR5+ICOS+ compared with CD8_{CXCR5−ICOS−} cell subsets are shown (*P < .05; **P < .01).