Continuous production of anti-host IgG antibodies contained in circulating IgG-anti-IgG complexes.

Weekly injection with antibody-coated pertussis led to the chronic production of serum complexes in mice. Mice bearing one allotype. Iga, received spleen cells from a congenic strain bearing another allotype, Igb, and weekly injections with Iga-coated pertussis. The serum complexes from these mice and from those receiving challenges alone were separated by ultracentrifugation at neutral and acid pH on sucrose density gradients and their fractions tested for their anti-Iga and Iga content. This revealed the presence of anti-host (Iga) allotype antibodies in fractions from mice that had received Igb cells but not from mice given Iga-coated pertussis alone. Iga allotype was detected in fractions from both groups. It is considered that anti-host allotype antibodies are continuously produced but that they cannot be detected in unfractionated serum because the antibody forms complexes with Iga. These findings are discussed in relation to rheumatoid disease in humans.