Heterogeneity of human peripheral blood monocyte subsets

In recent years the number of reports describing; phenotypically and functi onally distinct subsets of human blood leukocytes, and in particular of sub types of antigen-presenting cells has continuously increased. A great diver sity Tvas described not only for dendritic cells (DC), hut also for human b lood monocytes (Mo) and macrophages (Mac), Similar to DC, the different typ es of Mo subsets could be defined by distinct phenotypes and immunoregulato ry functions. The characterization of blood Mo subpopulations revealed that some of them exhibit common features with myeloid or lymphoid DC and tissu e Mac, but also demonstrate the existence of novel unique cell populations. The generation of lymphoid and myeloid DC and their heterogeneity has been the subject of recent reviews. Here we focus on Mo from human peripheral b lood and summarize the data (including our own) dealing with their phenotyp ic and functional, in particular immunoregulatory properties.