PDCD1 and diffuse large B-cell lymphoma: In our previous study implementing fluorescent multiplex immunohistochemistry (mIHC) in a large cohort of patients with DLBCL treated with R-CHOP, we found that T cell deficiency, natural killer (NK) cell deficiency, high percentage expression of PD-1 in CD8+ T cells, and PD-L1 expression in the TIME were associated with significantly poorer survival (18).