Long-term human peripheral blood monocyte cultures: establishment, metabolism and morphology of primary human monocyte-macrophage cell cultures.

Human peripheral blood monocytes were maintained in in vitro culture for periods up to 4 months using a non-human serum source. Monocytes were cultured in Dulbecco's modified Eagle's medium buffered with 20 mM HEPES and containing 10% horse serum and 10% foetal calf serum. The metabolic and morphological changes which occur in vitro were investigated using microtitre, Linbro and T 25 cultures. During culture, monocytes increased in size, had increased membrane activity as visualized by SEM, and differentiated into a morphologically heterogeneous population of fusiform and epithelioid shapes. These cell types retained the ability to phagocytose E glut and EA and to rosette with EA and EAC. Larger giant polynucleated cells were also observed during culture; many of these lacked the ability to bind or phagocytose inert or antibody-coated erythrocytes. Increases in lysozyme release and acid phosphatase activity also occurred during culture. Cultured monocytes exhibited characteristic profiles of leucine and uridine uptake with maximal activity observed by 5 days of culture. There was no detectable uptake of thymidine. Detailed analysis of regulatory processes involved in monocyte growth and differentiation could be performed with this in vitro system.