While all of our cells share an almost indistinguishable genome, the variation created by the epigenome makes sorting and tackling the heterogeneity of cell types in your favorite homogenate a bigger task than finding a Yeti in a snow storm. Now a search and rescue team from Brown University has utilized DNA methylation profiles to breathe new life into all those precious blood samples gathering freezer burn, and have deciphered the cell type signatures behind immune system modulation.

The Brown scientists used DNA methylation arrays to analyze human whole blood, and here’s what they uncovered:

First, by purifying leukocyte subsets from whole blood, the team identified signatures that can be used to distinguish the alphabet of the immune system cell types (T-cells, B-cells, NK cells, monocytes, eosinophils, basophils and neutrophils).

A bioinformatic based approach was created to quantify these these cell type signatures in whole blood, identifying a profile of only 20 CpG loci.

The team confirmed that their approach could accurately measure the cell type composition of peripheral whole blood through reconstruction experiments.

The team also verified the accuracy of their new approach by directly comparing to current ‘gold standard’ immune system quantification techniques, that make use of physical, optical, and proteomic properties of the cells.

Then, to put the icing on the cake, the team also demontrated that their approach is not affected by the storage of blood samples, which is a current major roadblock in utilizing previous gold standards. The authors conclude that their new technique can be used to accurately and reliably decipher cell mixture distributions in whole blood, by using only DNA rather than whole cells.

Get your cells sorted out over at Genome Biology, March 2014