The Effect Of Polypeptides From Casein On The Maturation Of Dendritic Cells

The polypeptides derived from casein are important biological active peptides(BAP), which have obvious immunostimulating properties. Polypeptides were separated from tryptic and peptic casein hydrolysates by ethanol sedimentation, ultrafiltration and two rounds of Sephadex G-25 chromatography. First, use Millipore mouse Cytokine kits to test the concentrations of 24 cytokines in serum of mouse, which treated with polypeptides were separated from tryptic casein hydrolysates (TCH) through oral administration, intraperitoneal injection, intravenous injection to study the effects of peptides on the cytokine network and the impacts of innate immune response . The results indicated that, the concentrations of most of cytokines in serum of mouse were grown besides the anti-inflammatory cytokines as IL-5,IL-9,IL-10,MIP-1αwere reduced in the oral administration group; similar to the intraperitoneal injection group. The results of intravenous injection group was significantly different compared with the other two groups, which show that the peptide go to blood directly but not thought mucosal immune system, and activate a variety of different signaling pathways in immunocyte then change the gene expression of cytokine . Second, bone marrow-derived dendritic cells(DCs), which were generated from male C57BL/6 mouse were stimulated by casein-derived polypeptides, and 24 hours later, cells were tested on flow cytometry . The stimulated DCs and T cells were co-cultured 96 hours, and T cells proliferation was assayed using CCK-8 kit .The result show that two kinds of casein-derived polypeptides were able to stimulate DCs to mature, but the stimulation was lower than the LPS which as a positive control .And mature DCs can stimulate T cell proliferation, indicating DCs had the ability to present of the polypeptide. The concentrations of IL-1α, IL-β, IL-2, IL-6, IL-12 in clear supernatant liquid were increased, and the concentration of TNF-α, IFN-γwere decreased, indicating the Th2 polarization of naive T. The result shows that the casein-derived polypeptides have a regulating function on the acquired immune function.