RESUMO
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.