Length of the peptide chain influences the immunomodulatory activity of peptides related to p53 protein

We have shown that the thymopoietin-like octapeptides derived from DNA-bind ing domain of p53 protein and of its mutated forms differ in their immunomo dulatory properties. A strong increase of immunostimulative activity was ob served for GMNRSPIL (mutated protein) in comparison with GMNRRPIL (wild-typ e of p53 protein) peptide. Here the elongated sequences of respective prote in fragments were synthesized and investigated by plaque forming cells and delayed type hypersensitivity tests. The change of immunomodulatory activit y toward immunosuppression was observed: NSSC(Acm)MGGMNRRPILTIITLE (1, wild -type) was inactive in both tests, and the C(Acm)MGGMNRSPILTIITLE (II) and YMC(Acm)NSSC(Acm)MGGMNRSPILTIITLE (III) (mutated p53 protein fragments) pep tides produced immunosuppression in plaque forming cells as well as in dela yed type hypersensitivity tests. (C) 1999 Elsevier Science Inc. All rights reserved.