Extra

HLA-DR

considered a pan-b lineage marker in leukaemia although the widespread expression limits its value where lineage is ambiguous the expression of HLA-DR may contribute to the assignment of b cell lineage in myeloid leukaemias the absence of HLA-DR can have value in identification of acute promyelocytic leukaemia but molecular typing is required for diagnosis details HLA-DR is typically expressed by macrophages b-cells and dendritic cells. HLA-DR presents antigen to t-helper cells serving to suppress t-helper cell responses and prevent the production of antibodies against self-antigens. HLA-DR is also expressed by early myeloid progenitor cells but expression is lost as they mature to promyelocytes. *myeloid leukaemias generally express HLA-DR is expression is expected to be absent from mature myeloid leukaemias such a apl and erythroid leukaemia *b-lineage leukaemias and lymphomas each generally express HLA-DR although expression is generally lost at the plasma cell stage *t-lineage all is generally HLA-DR negative although rarely mature t cell neoplasms may express HLA-DR