CD8A and neoplasm: For instance, pancreatic neuroendocrine tumors (Pan-NENs) differ from small intestine neuroendocrine tumors (SINENs) in terms of T cell infiltration and PD-L1 expression.182 Studies have shown that both tumor and non-tumor areas in Pan-NENs have a high level of T cell infiltration, including CD3+, CD45RO+ (Tms), and CD8+ T cells.