Comparative quantitation of anti-viral titers of polyclonal human IgG and (Fab′) 2 preparations by an enzyme-linked immunosorbent assay (ELISA): Pitfalls of using appropriate second antibodies

Abstract

When comparing anti-viral antibody titers of intravenous immunoglobulins (i.v.-Igs) comprising two 7S IgG preparations and one corresponding (Fab′) 2 product, the specificity of the second ab-peroxidase conjugate employed in the ELISA was found to be decisive for the experimental results. Abs specific for the whole IgG molecule, in contrast to the (Fab′) 2 specific ones, obviously contain populations recognizing epitopes localized on Cγ2 and Cγ3 domains, and, therefore, cause an underestimation of titers of the (Fab′) 2 preparation.