Green tea extract improves cyclophosphamide-induced immunosuppression in mouse spleen and enhances the immune activity of RAW 264.7 cells

Cyclophosphamide (CP) is mainly used to treat autoimmune diseases and cancer; however, it damages normal immune cells. Therefore, the effects of chemotherapy on CP are limited. Notably, green tea has been reported to effectively modulate immune function. Here, given the pharmacological properties of green tea, we evaluated the ability of green tea extract (GTE) to restore immunity suppressed by CP in vivo and to activate macrophages in vitro. GTE significantly improved the suppressed immune function, including spleen index and proliferation of spleen T lymphocytes, as revealed by histopathological examination and flow cytometry analysis. Moreover, GTE effectively activated RAW 264.7, as represented by the induction of nitric oxide, reactive oxygen species, and cytokine levels. GTE also increased the phosphorylation of mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B in RAW 264.7 cells. In conclusion, GTE ameliorated CP-induced immunosuppression in mice and stimulated immune activity in RAW 264.7 cells, possibly by activating the MAPK signaling pathway. These findings suggest that GTE has the potential to be used as a supplementary agent in chemotherapy for CP.