Isolation and characterization of a novel immunomodulating fraction from soybeans

A novel immunomodulating fraction, SP-MAF1, was isolated from soybeans as a polysaccharide-protein complex by hot water extraction followed by acid treatment, ethanol treatment, and chromatography on a DEAE-Sepharose CL-6B column, and was characterized in some biological activities. SP-MAF1 increased glycolysis and IL-1 production by macrophages, but did not affect TNF production. SP-MAF1 also increased splenocyte proliferation that was induced by LPS and ConA, and ConA-induced production of IL-2 by splenocytes. In an in vivo test, the mean survival times of SP-MAF1-treated mice bearing FM3A were significantly longer than those of non-treated group. Since SP-MAF1 affected macrophages and splenocytes but not tumor cell growth, this effect may be mediated by the host immune system. Furthermore SP-MAF1 had a capacity to suppress the TNBS-induced DTH reaction. These results suggested that SP-MAF1 could either enhance or suppress immune functions.