Relationship Between Fc Receptors and Ia Alloantigens: Analysis with a Sensitive Radioimmunoassay

Abstract

This paper describes the successful use of ¹²⁵I-labeled IgG aggregate to detect Ia-type alloantibodies in pregnancy sera. The blockade of aggregate uptake of a variety of normal mononuclear and leukemic cell types by anti-Ia alloantibodies is analyzed. Fc receptors and Ia alloantigens are clearly two distinct molecular entities. The association between Fc receptors and Ia alloantigens on a quantitative level seems to depend on a ligand-binding mechanism to control their interaction rather than the presence of a topographical molecular tandem arrangement.