The immunomodulatory activity of peptides related to the DNA contacting loop of p53 protein

Taking into account the sequence homology existing between thymopoietin II and the DNA-binding domain of p53 protein, a series of octapeptides was synthesized, related to the wild p53 type protein as well as to its mutated forms, appearing in some human tumours. The wild type octapeptide has immunostimulative activity with regard to the humoral immune response, but is inactive in the cellular immune response. The mutated peptides of p53 differ in their immunomodulatory activity from the wild type octapeptide. The Ser5 analogue of the wild peptide is a strong stimulant of the humoral immune response and enhances TNF-alpha production, while at the same time suppressing the cellular immune response. The data suggest that the mutations of p53, which favour tumour development and growth, may also change the immune activity of respective p53 fragments.