High numbers of fully functional cells are obtained from whole blood or buffy coat cells. The use of simple laboratory equipment and a relatively cheap reagent makes the described method a convenient approach to obtaining human monocytes. We propose here a simple two step procedure for obtaining highly purified human monocytes. The degree of lymphocyte contamination when separating monocytes by the adherence method is probably related to percentage of lymphocytes in PBMC, the amount of PBMC laid for adherence, number of washes, strength of washing and time of adhesion. These aspects can make this method variable from donor to donor and from researcher to researcher.
Alternative methods are immune-selection, centrifugal elutriation and density gradients.
Immune selection is too expensive for daily routine and for large volumes of blood. Centrifugal elutriation, although the method of choice for larger volumes of blood, requires expensive equipment and a specialized technician. Several kinds of density gradients are available, both continuous and discontinuous. Pumps and ultracentrifuges, in general expensive equipment, are necessary for performing continuos gradients. We report here on the results using a two step procedure with single gradients in each step.