Method for large scale isolation, culture and cryopreservation of human monocytes suitable for chemotaxis, cellular adhesion assays, macrophage and dendritic cell differentiation.

This paper presents an improved method of isolating, culturing and cryopreserving human monocytes in large quantity with high purity using standard laboratory centrifuges. Monocytes were isolated from 300 to 360 ml of heparinized human blood using a Double Density technique employing Ficoll Isopaque and 46% iso-osmotic Percoll. Yields of monocytes ranged from 75 to 205 million (from 300 to 360 ml of blood) with an average purity of 90.6%. The ability of fresh or frozen monocytes to adhere to endothelial cells in the presence of oxidized L-alpha-1-palmitoyl-2-arachidonosyl-sn-glycero-3-phosphocholine (oxPAPC) or lipopolysaccharide (LPS) did not differ and no significant difference in response to the chemotactic stimulant N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) was observed. We define a useful method for the culture and differentiation of fresh or frozen monocytes isolated by this method, into macrophages as judged by morphology, expression of the macrophage marker SRA-1 and induction of inflammatory genes TNF-alpha, IL-6 and COX-2. Also, fresh or frozen Double Density isolated cells can be successfully differentiated into dendritic cells in the presence of GM-CSF and IL-4 as judged by the expression of the hallmark surface proteins CD1a and DC-sign and the absence of CD14. This method also yields a pure population of lymphocytes.