Synthetic Fc peptide-mediated regulation of the immune response. I. Characterization of the immunomodulating properties of a synthetic 23-amino acid peptide derived from the sequence of the CH3 domain of human IgG1.

A synthetic 23-amino acid peptide derived from the CH3 domain of human IgG1 was found to be a potent adjuvant as well as a polyclonal activator. The Fc peptide was found to enhance human and murine humoral, and T cell-mediated immune responses. Moreover, in vivo administration of Fc peptide enhanced murine natural killer cell activity. The synthetic Fc peptide was found to be more potent, on a molar basis, than native Fc fragments in inducing polyclonal antibody production and potentiating immune responses.