Differential expression of major histocompatibility complex class Ia, Ib and II molecules on monocytes and monocyte-derived dendritic and macrophagiccells

Blood monocyte derived antigen presenting cells (APC) such as dendritic cel ls and macrophages are considered as major promising tools for antitumoral immunotherapy. In order to contribute to their phenotype characterization, we have precisely investigated their levels of expression of MHC class Ia, Ib (HLA-G) and II molecules using mainly flow cytometry quantification assa ys. APC were generated from monocytes cultured for 7 days in the presence o f GM-CSF and IL-4 or M-CSF. These cells, which exhibited known morphologica l and immunological features of dendritic cells and macrophages respectivel y, were evidenced to display high expression of MHC class Ia and class II a ntigens in comparison to that found in monocytes. Dendritic cells and macro phages thus expressed 2-fold more and 4-fold more MHC class Ia molecules an d 5-fold and 3-fold more MHC class II DR molecules than parental monocytes. In addition, expression of MHC class II DP and DQ molecules, not or only b arely detected in monocytes, was clearly demonstrated in the two kinds of A PC. In contrast, monocytes, dendritic cells and macrophages failed to expre ss MHC class Ib HLA-G antigen. The up-regulation in monocyte-derived APC of MHC class Ia and II molecules mediating the presentation of antigen peptid es to lymphocytes fully supports the interest of such APC in antitumoral im munotherapy. Human Immunology 60, 591-597 (1999). (C) American Society for Histocompatibility and Immunogenetics, 1999. Published by Elsevier Science Inc.