Molecular Bases of Passive Sensitization

Abstract

Summary The effect of chemical procedures designed to break the disulfide linkages of γ-globulins on passively sensitize guinea pig skin was studied with a human γ-globulin-rabbit anti-HGG system. Human (antigen) and rabbit (antibody) γ-globulins lost sensitizing activity after treatment with mercaptoethanol followed by sulfhydryl blocking agents such as iodoacetate or iodoacetamide, as determined by passive cutaneous anaphylaxis tests in guinea pigs. Treatment with either mercaptoethanol or iodoacetate alone did not affect their sensitizing activity. Mercaptoethanol-iodoacetate treated proteins, either as antigen or antibody elicited cutaneous anaphylactic reactions in guinea pigs previously sensitized with unmodified γ-globulins as antigen or antibody and also showed precipitin reactions with the complementary reagents comparable to reactions using unmodified proteins. The complement-fixing properties of the HGG-anti-HGG systems were unaffected by the treatment of either antigen or antibody by mercaptoethanol and iodoacetate. The results suggested that irreversible cleavage of disulfide linkages in human and rabbit γ-globulin molecules was correlated with a decrease in their affinity for guinea pig tissues.