Molecular heterogeneity of i-a^b molecules: Analysis of i-a^b subsets with monoclonal antibodies

In the mouse there are two Ia molecules, A and E, which are encoded by two alpha genes and two beta genes. However, previous studies from this laboratory suggested the existence of multiple forms of Ia molecules. In this report, we have investigated the molecular heterogeneity of A^b molecules by isolating and analyzing subpopulations of Ia molecules. By using monoclonal antibody affinity columns, we have isolated four distinct subpopulations of A^b molecules. These subpopulations representing a significant fraction of the total A molecules were negative for determinants recognized by one or more anti-A^b monoclonal antibodies. Possible mechanisms of the origin of these molecules are discussed.