PDCD1 and neoplasm: We then used a mouse model to detect immune cell infiltration and relevant protein expression by flow cytometry and immunohistochemistry under anti-PD-1 treatment after overexpression of FLT3LG. The serum FLT3LG expression in LUAD patients was detected via ELISA, and PD-L1 expression in tumor samples was detected by immunohistochemistry.