Isolation of IL-12p70-competent human monocyte-derived dendritic cells.

Diverse methodologies ranging from experimental immunological studies to immunotherapy involve the application of human monocyte-derived dendritic cells (moDCs). Considerable donor-dependent variations in the moDC production of IL-12p70 affect the outcome of these methodologies. It has been shown that moDCs generated under standard conditions develop into two subsets based on CD1a-expression with the CD1a+ moDCs being the main IL-12p70 producers. This has however not been generally accepted, which we show here because the subset described as CD1a-negative does express CD1a, but at a lower level than the other subset. We further characterize the phenotype of these two subsets, showing that the CD1a-hi subset has a greater immunogenic phenotype, making this subset more suitable for immunotherapy. The two subsets have previously been separated by cell sorting, but as this technique is not available to many laboratories and has incompatibility with clinical settings, a more widely useable technique is warranted. Therefore we tested if magnetic-activated cell sorting is useful for the purpose, and show that it is possible to isolate IL-12p70-competent CD1a-hi moDCs to a <92% purity, irrespective of the starting purity.