Differential expression of HLA-DR and HLA-DQ antigens on normal cells of the myelomonocytic lineage.

We have previously shown that HLA-class II antigens have a differential expression on acute myeloblastic leukaemia (AML) blasts. These cells express HLA-DR molecules but the HLA-DQ antigens are undetectable. In this paper we study the expression of HLA-DR and HLA-DQ antigens, using monoclonal antibodies (MoAbs), on normal cells of the myelomonocytic lineage: the common myelomonocytic progenitor (CFU-GM) and the monocytes, by techniques of inhibition of CFU-GM growth and double immunofluoroscence, respectively. The results show that HLA-DR and HLA-DQ antigens are differentially expressed on normal myelomonocytic cells. While HLA-DR molecules are expressed on CFU-GM and on the majority of peripheral blood monocytes, HLA-DQ antigens are not expressed on CFU-GM and only present on a subpopulation of monocytes. This data further confirms that HLA-DR and HLA-DQ molecules are coded by different genes with independent regulation of the gene expression not only on myeloid leukaemias but also on normal cells of the myelomonocytic lineage.