Differential expression of HLA‐DR and DR‐linked determinants on human leukemias and lymphoid cells

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Abstract
Leukemic and normal hemopoietic cells were examined with the monoclonal antibodies DA2 and Genox 353 for the presence of HLA‐DR and DR‐linked (DC/MB) determinants, respectively. Although most non‐T acute leukemias and leukemic cell lines expressed the monomorphic DR determinant detected by DA2, fewer than expected expressed the DR‐linked polymorphic specificity detected by Genox 353. TdT+ lymphoid precursors from normal bone marrow were also DA2+ but Genox 353−. T cells and thymocytes which were DA2−, Genox 353− became DA2+, Genox 353+ after activation in vitro. Immunoprecipitation using DA2 and Genox 353 gave bands on polyacrylamide gelelectrophoresis which were of different molecular weights. In addition, DA2 could absorb out Genox 353 determinants from a cell lysate whereas Genox 353 could not absorb out DA2 determinants. It is concluded that DA2 and Genox 353 detect HLA‐DR and DR‐linked (DC1/MB1) determinants, respectively, and that these are differentially expressed on hemopoietic cells during differentiation.