Human Ia molecules carrying DC1 determinants differ in both alpha- and beta-subunits from Ia molecules carrying DR determinants

Several genetic markers of human la molecules, each recognized by specific alloantisera, have been defined: DR1,2,3,4,5,w6,7,w8,w9,w10. They are controlled by a single locus, HLA-DR. In addition alloantigenic specificities have been identified which are associated, at the population level, with two or more of the above DR specificities. They have been called 'supertypic specificities'. DC1 supertypic specificity (nomenclature equivalents: MB1, MT1, LB12) has attracted particular attention, because although exhibiting a population association with DR1, 2 and w6, DC1 is carried by a different molecular species. Possibly, DC1 may represent the first genetic marker of a locus different from the DR locus but in strong linkage disequilibrium and therefore probably closely linked to it. Here we report the development of a monoclonal reagent specifically directed against DC1 and its utilization in a structural analysis of DC1 molecules as compared with la molecules carrying different DR determinants.