A β-glucan from Aureobasidium pullulans enhanced the antitumor effect with rituximab against SU-DHL-8.

β-Glucans affect the immune system and have antitumor activity; therefore, they are being investigated as immunomodulators and chemotherapeutic adjuvants. In this study, we investigated a specific β-glucan, exopolysaccharide (EPS-1) derived from Aureobasidium pullulans (CGMCC 20363), to investigate its impact on the efficacy of rituximab against diffuse large B cell lymphoma (SU-DHL-8 cells) in vitro and in vivo. The results show that compared to rituximab alone, EPS-1 enhanced the inhibition of SU-DHL-8, had antitumor effects in vivo, and improved the response of the immune system of the host. RNA sequencing results reveal that EPS-1 had a chemotactic effect on T cells through the JAK-STAT signaling pathway and recruited immune cells into tumor tissues. EPS-1 also played an antitumor role through the mitochondrial and death receptor Fas-related apoptotic pathways. In summary, EPS-1 may be an effective adjuvant to treat diffuse large B cell lymphoma in combination with rituximab.