OBJECTIVETo study the effect of Feiji Recipe (FR) intervening indoleamine 2,3-dioxygenase (IDO) induced immune escape on the murine model of Lewis lung carcinoma. Methods Totally 48 C57BL/6 mice inoculated with Lewis lung cancer cells transfected with human (enhanced green fluorescent protein,EGFP)-IDO gene were divided into four groups according to radom digit table, i.e., the model group (administered with normal saline by gastrogavage) , the Chinese medicine group (treated with FR Decoction at the daily dose of 100 mg/g by gastrogavage), the 1-methyl-D-trytaphan (1-MT) group (administered with 1-MT mixed liquor at the daily dose of 100 mg/kg by gastrogavage), and the Paclitaxel group (treated with Paclitaxel at the daily dose of 15 mg/kg by peritoneal injection), 12 in each group. The intervention was started from the 2nd day of modeling. The survival time was observed in 24 of them. Ratios of CD4+ CD25+ FoxP3+ regulatory T cells (Treg) in the spleen were detected in the rest 24 mice by flow cytometry respectively.

RESULTSCompared with the model group, the survival time was significantly prolonged in the Chinese medicine group and the 1-MT group (P < 0.01); ratios of Treg cells remarkably decreased in the Chinese medicine group, the 1-MT group, and the Paclitaxel group (P < 0. 01). Compared with the Paclitaxel group, the survival time was significantly prolonged in the Chinese medicine group and the 1-MT group (P < 0.01); ratios of Treg cells decreased significantly in the 1-MT group (P < 0.05).

CONCLUSIONFR could inhibit the proliferation of lung cancer cells and immune eseape, improve the immune function, and prolong the survival of tumor-bearing mice.