3 POPULATIONS OF CELLS WITH DENDRITIC MORPHOLOGY EXIST IN PERIPHERAL-BLOOD, ONLY ONE OF WHICH IS INFECTABLE WITH HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1

Conflicting data have been reported with regard to the infectability, dysfunction, and depletion of dendritic cells (DCs) in human immunodef iciency virus (HIV) disease. These discrepancies could potentially be explained by the existence of multiple subsets of cells with dendritic morphology in peripheral blood. The isolation of DCs in humans is acc omplished through negative selection until a morphologically pure popu lation is obtained. Recently, DC precursors purified from peripheral b lood by negative selection have been observed to develop into function ally and morphologically mature DCs. In this report we identify three populations of cells in peripheral blood that have or can develop a de ndritic morphology. The first population, when allowed to mature in cu lture, develops a dendritic morphology and gains the expression of HB1 5, a marker of DCs in blood, thymus, skin, and lymphoid organs. The se cond population expresses HB15 and has the phenotypic and morphologic characteristics of mature DCs. The third population is morphologically very similar to mature DCs but does not share the same T-cell-stimula tory activity and is the only population that is infectable with HIV. Understanding the heterogeneity of cells of dendritic lineage and/or m orphology in the peripheral blood will aid in understanding their role as antigen-presenting cells in general and as potential participants in the immunopathogenesis of HIV disease.