CD4 and malignant colon neoplasm: We previously found that B cell PD-L2 (B7-DC) increased in spleen, blood, and BM with age, that aged PD-L2+ B cells regulate CD4+ T cell functions distinctly from young in a PD-L2-dependent manner and that PD-L2+ B cells inhibit subcutaneous MC38 colon cancer growth.74 Our current data show increased PD-L1, PD-1, and CD80 expression in aged versus young B cells but similar PD-L2 expression.