Since dendritic cells (DC) were recognized as playing an important role in the induction of cellmediated responses [1], there has been a rapid growth in research into the function of these cells and methods for their purification. Gradients of either albumin or metrizamide, although providing an effective enrichment of DC, tended to cause some functional alteration of the cells (see ref 2 for details). 

However, because cells are much more tolerant of Nycodenz, this iodinated density gradient medium rapidly became established as the medium of choice for DC cell purification from peripheral blood and from lymphoid tissues. 

More recently methods have been developed for isolation of DC from tissues in iodixanol gradients because of the even higher tolerance of this solute by cells. 

Compared to other cell types in tissues such as spleen, thymus, lymph nodes etc., the DCs have a low density and one of the most commonly Nycodenz-based techniques is simply to isolate lowdensity cells by layering the disaggregated cell suspension over a barrier of density 1.077-1.080 g/ml (e.g. refs 3-5).