Single‐cell analysis revealed that BAMBIhigh DLBCL cells engage CD4+ T cells via TGFB1‐TGFBR2 pair, with TGFBR2 enriched in exhausted subsets of CD4+ T cells and shaping their dysfunctional fate. The gene discussed is TGFBR2; the disease is diffuse large B-cell lymphoma.