Immunoglobulin Production Stimulating Effect of Soy-Derived Proteins

摘要

We found that a novel and potent immunoglobulin production stimulating factor (IPSF) was contained in soybean trypsin inhibitor (STI) preparation. The IPSF significantly enhanced IgM production by mouse spleen lymphocytes. To clarify the mechanism ofthe IPSF activity, the effect of the IPSF on the expression of some cytokines was examined. The IPSF promoted the expression of interleukin-6 (IL-6) and IL-10 mRNA. The IgM production stimulating activity was partially but significantly suppressed by IL-6 neutralization antibody. These data suggest that the IPSF stimulates IgM production, at least partially, via the enhancement of IL-6 production. To reveal the IPSF is not STI, STI preparation was fractionized by anion-exchange chromatography and the IPSF activity of each fraction was analyzed. Active fraction was eluted distinct fraction containing STI. Active fraction contained some proteins whose molecular weights were about 29 kDa. These suggest that IPSF in STI preparation is not STI itself but contaminants. Taken together, the about 29 kDa protein and/or its complexes with several proteins exist in STI preparation could have a potent IPSF activity and the activity was exerted, at least partially, via stimulation of IL-6 production.