The use of synthetic gamma-chain peptides in the localization of the binding site(s) on human IgG1 for the Fc receptors of homologous monocytes and heterologous mouse macrophages.

In an attempt to locate precisely the sites on human IgG responsible for binding to monocytes and macrophages, synthetic peptides representative of sequences of the human gamma-chain have been used as potential inhibitors of human [125I]IgG1 binding to human monocytes and mouse macrophages. One peptide, comprising the sequence of Tyr407--Arg416 of the C gamma 3 domain, showed the same maximum inhibition of [125I]IgG binding to mouse macrophages as unlabelled IgG. Two peptides derived from sequences in the C gamma 2 domain were shown to exhibit limited inhibition of Igg binding to homologous human monocytes.