Immunological Unresponsiveness to Specific Antigenic Determinants in Human γ G Globulin. ∗

Abstract

Summary

Immunological unresponsiveness to HGG fragments was induced by intravenous administration of 5 mg soluble antigen. Concomitantly the animals were sensitized to the intact HGG molecule, by injection of 60 μg protein, in complete Freund's adjuvant, into the rear footpads. The immune response was followed at weekly intervals by delayed hypersensitivity measurements, by PCA ti-trations, by gel diffusion precipitin analysis and by radioimmunoelectrophoresis. It was found that when either F_ab or F_c fragments were given intravenously, together with an injection of HGG in the footpad, the animal became tolerant to those antigenic determinants represented in the fragments, but was simultaneously sensitized to the other antigenic sites on the molecule.

When papain digested HGG (free from undigested material) was administered intravenously, however, antibodies directed against the whole intact molecule, but not against either F_ab or F_c fragments, were demonstrable. It would appear that the animals' immune mechanism is capable of subtracting' those determinants shared by both suppressive and sensitizing antigens, from those found in the sensitizing antigen alone.