Heterogeneity of HLA-DR2: definition of two subtypes by serological and cellular techniques

We have used the serological and cellular (PLT) techniques to investigate the heterogeneity of HLA-DR2. The serologic studies demonstrate that DR2 can be subdivided into two specificities based on the patterns of reactivity with the Ninth Workshop serum, 9w555. These two DR2 subtypes were also recognized by cellular assay utilizing PLTs generated between HLA-DR2, DQ-identical, DP-identical or incompatible individuals. The data, therefore, suggest the existence of two alleles of DR2, DR2.1 (long) and DR2.2 (short).