Intravascular metabolism of normal and mutant mouse immunoglobulin molecules

Abstract

The metabolism of IgG immunoglobulins in the body is tightly regulated in order to maintain their intravascular concentration. Different subclasses may have different intravascular half‐lives, and in the mouse, passively administered IgG_2b disappears from the circulation more rapidly than IgG_2a. We have attempted to localize the sequences in the constant region which are responsible for this difference by examining the intravascular metabolism of mutant immunoglobulins that were generated in tissue culture and have undergone deletions of individual constant region domains or contain different combinations of γ_2b and γ_2a C_H2 and C_H3 domains. Our results suggest that the regulation of intravascular metabolism is complex but indicate that sequences in the C_H3 domain are important in determining the different intravascular half‐lives of IgG_2b and IgG_2a antibodies in the mouse.