We have reported previously that some proteins such as lactoferrin and lysozyme control the immune system via immunoglobulin (Ig) production. In the course of the study about the function of dietary proteins and peptides, Ig production-stimulating activity of an unknown protein contained in soybean trypsin inhibitor (STI) preparation was found. Thus, we examined the activity of the unknown activator and the mechanism of the activity. The factor significantly elevated IgM production by mouse spleen lymphocytes in a dose-dependent manner. In addition, the unknown activator up-regulated the expression of interleukin (IL)-6 and IL-10 mRNA. And IgM production enhancing activity of STI was significantly suppressed by neutralization of IL-6. Then, to clarify whether STI itself is the active compound or not, STI was fractionized by gel filtration chromatography. We found that the activity the content of STI did not correlate with and the active fractions contained some proteins whose molecular weight is more than 20 kDa. These suggest that an unknown activator exists in STI preparation.
All Science Journal Classification (ASJC) codes
- Food Science