Consistent with reports of disparate B cell differentiation states between blood and tumors,7 17 35 scRNAseq (single-cell RNA sequencing) analyses of melanoma lesion samples36 revealed B cells and plasma cells pre-CPI and post-CPI with class-switched phenotypes, and expressing CR2/CD21, CD95/Fas and TGFβ, while few cells expressed PD-L1 and IL-10. The gene discussed is TGFB1; the disease is melanoma.