Experimentally produced antibodies to the pepsin site of IgG due to untreated autologous IgG in immune complexes

Abstract

By immunizing rabbits with immune precipitates containing autologous IgG as the antibody part, most animals produced both rheumatoid factor-like antibodies and antibodies to human and rabbit F(ab')₂ IgG. The latter antibodies resembled the human antibodies to the pepsin site of IgG by not reacting with untreated IgG and by reacting with immune precipitates made from autologous and homologous antibodies. The rabbit antibodies to the pepsin site of IgG in most cases consisted of a mixture of IgG and IgM, while the human antibody is usually pure IgG.

The investigation demonstrated that in addition to rheumatoid factor, other human anti-IgG antibodies may also be due to antigenic stimulation by autologous IgG in immune complexes.