PDCD1 and neoplasm: To our expectation, B cells sorted from Hepa1‐6 orthotopic transplanted liver tumors can augment the efficiency of tumor killing by T cells and strengthened the efficacy of anti‐PD‐1 in vitro (Figure S8G, Supporting Information), possibly also through increased proliferation, strengthened expression of IFN‐γ and Perforin, and down‐regulation of PD‐1 expression in CD8+T cells (Figure S8H, Supporting Information).