Abstract: ObjectiveTo investigate the expression and prognostic value of lymphocyte activating gene 3（LAG-3） and tumor infiltrating lymphocytes(TILs) in esophageal squamous cell carcinoma(ESCC). 
MethodsThe hematoxylin-eosin staining(HE) sections of 60 patients with ESCC who were not treated before operation in our hospital were analyzed retrospectively, and the TILs HE staining was interpreted. Meanwhile, immunohistochemical staining for LAG-3 was performed, and the results were observed and interpreted under the light microscope. The expression of LAG-3 and TILs in ESCC was analyzed. The correlation and their function in the prognosis of patients with ESCC were statistically analyzed. 
ResultsImmunohistochemical results showed that the positive rate of LAG-3 in ESCC was 38.3%(23/60), and LAG-3 was only expressed on TILs, but not on tumor cells. Reverse transcription polymerase chain reaction(RT-PCR) showed that the relative expression of LAG-3 in ESCC was higher than that in adjacent normal esophageal mucosa. In 60 patients with ESCC, there were different degrees of tumor lymphocyte infiltration, including 21 cases of low TILs, 27 cases of moderate TILs and 12 cases of high TILs. The expression of LAG-3 was significantly correlated with TILs, tumor differentiation and TNM stage. Kaplan Meier survival analysis showed that the PFS was related to TNM stage, lymph node status, LAG-3 and TILs, suggesting significant differences(P＜0.05). Multivariate COX regression analysis showed that the PFS was related to TNM stage and LAG-3, and the difference was statistically significant(P＜0.05). 
ConclusionThe high expression of LAG-3 is associated with the improvement of survival rate, and LAG-3 is an independent predictor of survival, suggesting that LAG-3 may be a useful immune marker for the prognosis of ESCC.

Key words: esophageal neoplasms, carcinoma, squamous cell, lymphocyte activation