THE IMMUNOMODULATORY ACTIVITY OF TETRAPEPTIDES AND TRIPEPTIDES OF TUFTSIN-KENTSIN GROUP

It was found that tuftsin (Thr-Lys-Pro-Arg) and its tetrapeptide analo gues with the same amino acid composition, but different sequences, de monstrate immunosuppressive activity for the humoral, but not (excepti ng the Thr-Lys-Arg-Pro tetrapeptide) for the cellular, immune response . The splitting of N-terminal residues from these tetrapeptides leads, however, to formation of tripeptides that are active in both humoral and cellular immune response tests. Thus, the biological degradation o f peptides of the type investigated can seriously modulate their immun obiological activities. We also found that tetrapeptides Thr-Arg-Lys-P ro and Thr-Lys-Arg-Pro, as well as tripeptides Arg-Lys-Pro and Lys-Arg -Pro, distinctly differ in their immunomodulatory activities, although the structural differences consist in this case only in the displacem ent of two basic amino acid residues.