Ia molecular localization of the DRw52 allodeterminant and the DRw52-like determinants defined by monoclonal antibodies.

DRw52 (formerly MT2) is a human Ia alloantigen that is expressed in linkage disequilibrium with DR3, 5, w6, and w8. Although there is general agreement that the DRw52 determinant resides on biochemically defined DR molecules, conflicting evidence exists regarding whether DRw52 resides on one or both DR molecules, DQ and DR molecules, or DR and BR molecules. Six anti-DRw52 allosera and three DRw52-like monoclonal antibodies were used to identify the Ia molecules that bear the DRw52 and DRw52-like determinants from DR5 and DRw6 homozygous cells. Based on these two-dimensional gel studies, the DRw52 allodeterminant appears to reside on a subset of DR molecules from DR5 and DRw6 cells. In contrast, the determinants defined by the three anti-DRw52-like monoclonal antibodies were found to reside on one DR molecule, on the second DR molecule, or on both DR molecules, respectively. Therefore, there is considerable complexity of Ia antigenic determinants that are associated with DR3, 5, w6, and w8 at the population level.