HEAVY CHAIN SUBCLASSES OF HUMAN γG-GLOBULIN

Abstract

Two anti-genic types of naturally occurring proteins related to the papain produced Fc fragment of G globulin have been studied. Most normal and myeloma [gamma]G globulins are related to one or the other of these proteins, based on antigenic and structural characteristics of their heavy chain. Molecules bearing the determinant "Cr" are approximately 10 times as abundant as those bearing the determinant termed "Zu" in pools of normal [gamma]G globulin and among a large group of [gamma]G myeloma globulins. Both populations have properties of typical [gamma]G globulin antibodies. Splenic cells, stained for these 2 populations with specific fluorescent antibody preparations, are found to contain one or the other of the 2 populations of [gamma]G globulin, but not both. Approximately 10 times as many cells contain the Cr determinant as contain the Zu determinant.