Objective To investigate the expression and clinical significance of programmed death receptor-1 (PD-1)and lymphocyte activation gene-3 (LAG-3) in the tumor microenvironment of follicular lymphoma (FL).Methods A total of 22 patients with FL diagnosed by pathology in the First Affiliated Hospital of University of Science and Technology of China from 2017 to 2022 were included.The expression levels of PD-1,LAG-3,programmed cell death-ligand 1 (PD-L1),cell surface chemokine receptor 4 (CCR4),cell surface chemokine receptor 3B (CXCR3B) and forkhead protein P3 antibody(FOXP3)in FL patients were detected by immunohistochemistry.The relationship between PD-1,LAG-3 and clinicopathological features and prognosis of FL patients was analyzed,and the correlation between each factor was analyzed.Results The levels of β2 microglobulin (β2-MG)in PD-1 high expression group and LAG-3 high expression group were higher than those in low expression group,and the differences were statistically significant (P＜0.05).The levels of lactate dehydrogenase (LDH)and β2-MG in PD-1/LAG-3 double high expression group were higher than those in PD-1/LAG-3 single high expression group and PD-1/LAG-3 double low expression group,and the differences were statistically sig-nificant (P＜0.05).Correlation analysis showed that in FL tissues,the expression level of PD-1 was positively correlated with the expression levels of LAG-3,CCR4 and CXCR3B (r=0.432,0.440,0.506,P＜0.05),but not with the expression levels of PD-L1 and FOXP3(P＞0.05).The CD8+T cell count in PD-1 high expression group,LAG-3 high expression group and PD-1/LAG-3 co-high expression group was less than that in the corresponding low expression group,and the differences were statistically significant(P＜0.05).Further correlation analysis results showed that PD-1 expression,LAG-3 expression and PD-1/LAG-3 co-expression were negatively correlated with CD8+T cell count(r=-0.631,-0.425,-0.552,P＜0.05).The results of survival analysis showed that the progression-free survival(PFS)and overall survival(OS)of LDH low expression group were better than those of LDH high expression group,and the PFS and OS of PD-1 low expression group,LAG-3 low expression group and PD-1/LAG-3 double low expression group were better than those of high expression group,and the differences were statistically significant (P＜0.05).Conclusion The high expression of PD-1 and LAG-3 is related to the higher level of clinical test indexes and poor survival prognosis of FL patients.Immune checkpoints such as PD-1 and LAG-3 are co-expressed in the tumor microenvironment and affect T cell counts.