Identification and characterization of HRS cells. (A) A representative cHL with CD15⁺/CD30⁺ HRS cells identified by manual gating. (B) HRS cells from each analyzed primary cHL (1-7). HRS cells express CD15⁺ and CD30⁺. CD4⁺ T cells, CD8⁺ T cells, or B cells from the same primary cHL samples lack CD15⁺ and CD30⁺ expression. PAX5⁺ is expressed by HRS cells and B cells. PD-L1 and pSTAT1 are expressed by HRS cells from all examined cHLs. These markers are absent or reduced in the other cell subsets.