Immunogenicity and effector functions of glutaraldehyde-treated rabbit and mouse immunoglobulin G

Rabbit and mouse IgG treated with glutaraldehyde (GA) were immunogenic in homologous species. Glutaraldehyde treatment induced in the IgG molecule two types of antigenic determinants. One of them was found on the monomeric fraction of GA-treated rabbit IgG (haptenic determinant) and the other on the polymeric fraction (structural determinant). The haptenic determinants were found also on monoaldehyde-treated rabbit IgG and GA-treated Fab and Fc fragments. It was demonstrated that rabbit and mouse antibodies are specific for GA-treated IgG and have species specificity. While GA treatment did not alter the antigen binding capacity of rabbit IgG antibody, its effector functions (except protein A binding) were much affected. Thus it was found that GA treatment enhances IgG ability to react with rheumatoid factor, reduces drastically its capacity to activate the complement system, abolishes the cytophilic properties of IgG and accelerates its catabolic rate. The possible blocking effect of GA on the amino acid residues (mainly Lys) situated in or very close to the effector sites of the IgG molecule is suggested.