Journal of Leukocyte Biology 43:51-59 (1988) © 1988 Alan R. Liss, Inc. Identification of Nonadherent Mononuclear Cells in Human Cord Blood

We describe a population of nonadherent cells in neonatal cord blood that, upon in vitro cultivation, develop into monocyte-macrophages. These cells initially are negative for nonspecific esterase cytoplasmic activity, lack the monocyte marker MO.2, fall into smaller, nonmonocytic cell size areas, as determined by fluorescence-activated cell sorter (FACS)-assisted size analysis, and differentiate into macrophages under nonsti-mulatory culture conditions (in the absence of exogenous colony stimulating factors, <0.1 ng/ml endotoxin, and growth in suspension). In contrast to the adherent, commit-ted macrophage precursors in cord blood, which differentiate into macrophages after 2-3 days of culture, the nonadherent precursor does not acquire monocyte-macrophage characteristics until day i4 of culture. Earlier induction is achieved by adding the monocyte-activating agents lipopolysaccharide or i,25 dihydroxyvitamin D3 to cultures. Key words: cord blood, macrophage differentiation, FAC