Cytokine-inducing activity of a proline-rich polypeptide complex (PRP) from ovine colostrum and its active nonapeptide fragment analogs.

A complex of proline-rich polypeptides (PRP) was isolated from ovine colostrum in our laboratory and was shown to possess immunomodulatory properties and psychotropic activity, including beneficial effects in the treatment of Alzheimer's disease. A nonapeptide fragment (NP): Val-Glu-Ser-Tyr-Val-Pro-Leu-Phe-Pro, isolated from the chymotryptic digestion products of PRP, and its C-terminal fragment, a hexapeptide (HP): Tyr-Val-Pro-Leu-Phe-Pro also exhibited immunoregulatory activity. Although NP and HP expressed activity similar to that of PRP in studies on humoral and cellular immune responses, in other immune processes, e.