The objective of the current study was to determine the effects of arabinoxylane and PSP on mouse splenocytes, T cells, B cells and macrophages in vitro. Arabinoxylane and PSP directly induced the proliferation of spleen cells in a dose-dependent manner and increased IFN-${gamma}$ synthesis. Especially, PSP induced IL-2, IL-4 and IL-10 production, Both arabinoxylane and PSP increased PFC (plaque forming cell) and RFC (rosette forming cell) formation. Arabinoxylane was not induced the proliferation of T cells, but PSP directly induced the proliferation of T cells in a high dose. Arabinoxylane and PSP increased the proliferation of B cells and the phagocytic effects of macrophage. When arabinoxylane and PSP were used in macrophage cell line stimulation, there was a marked induction of NO synthesis in a dose-dependent and an increased TNF-$alpha$ and IL-6 synthesis. Especially, PSP also induced IL-1$eta$ production. When arabinoxylane and PSP treated in macrophage cell line, there was induction of MHC class II expression. These results suggest that the capacity of arabinoxylane andPSP seem to act as a potent immunomodulator causing augmentation of immune cell activity, and with the absence of notable side-effects, arabinoxylane and PSP could be used as a biological response modifier having possible therapeutic effects against immunological disorders.