Effect of Acorus calamus L. Polysaccharide on CD274 and CD326 Expression by Lewis Lung Carcinoma Cells in Mice

Tumor cells can maintain their growth via immunosuppression and escape from host antitumor immunity by controlling the PD-1/PD-L1 system. Expression of PD-L1 (CD274) is an inhibitory signal for T cells, while the increase in CD326 expression in the tumor tissue correlates with metastasis development. The experimental preparation on the basis of α(1,2)-L-rhamno-α(1,4)-D-galactopyranosyluronan from Acorus calamus L. produces an antitumor effect: it reduces tumor node size and the number and area of metastases after transplantation of Lewis lung carcinoma. Using flow cytometry, we demonstrated a decrease in the population of tumor cells expressing surface CD274 (PD-L1) and CD326 antigens after 20-day course of α(1,2)-L-rhamno-α(1,4)-D-galactopyranosyluronan.