INHIBITION OF MITOGEN-INDUCED PROLIFERATIVE RESPONSES OF LYMPHOCYTES BY BOVINE KAPPA-CASEINOGLYCOPEPTIDES HAVING DIFFERENT CARBOHYDRATE CHAINS

Bovine kappa-caseinoglycopeptides (i.e. residues 106-169, CGP) were pr epared from K-casein digested with rennin and a commercial whey protei n concentrate. CGP from whey protein concentrate was further divided i nto seven CGP fractions having different carbohydrate compositions usi ng FPLC. Unfractionated CGP inhibited lipopolysaccharide (LPS)- and ph ytohaemagglutinin (PHA)-induced proliferative responses of mouse splee n cells and rabbit Peyer's patch cells. The unfractionated CGP also in hibited antibody responses to sheep red blood cells in mouse spleen ce ll cultures. However, seven CGP fractions having zero to five N-acetyl neuraminic acid (NANB) residues had different inhibitory effects on bo th LPS- and PHA-induced proliferative responses of mouse spleen cells. The inhibitory effect on PHA-induced proliferative responses increase d with increasing numbers of NANA residues, whereas that on LPS-induce d proliferation was highest with the CGP fraction having two NANA resi dues. Both inhibitory effects decreased significantly after neuraminid ase or chymotrypsin digestion. These findings indicate that both the c arbohydrate (particularly the NANA residues) and the polypeptide porti ons are essential for inhibitory effects on LPS- and PHA-induced proli ferative responses of mouse spleen cells.