These finding were not unique to liver tumors, because analysis of CD4+CD3+ human melanoma TILs (TILMel) across 48 lesions (Sade-Feldman et al., 2018) identified a cluster enriched in Isc-characteristic genes (of which 27% are PDCD1+), among other populations (Figure S6C). Here, CD4 is linked to melanoma.