ROVIDENCE, R.I. [Brown University] When a person becomes sick or is exposed to an unwelcome substance, the body mobilizes specific proportions of different immune cells in the blood. Methods of discovering and detecting those profiles are therefore useful both clinically and in research. In a new paper in the journal Genome Biology, a team of scientists describes a new and uniquely advantageous way to detect them.
All the current means of counting immune cells in a blood sample require whole cells, said Karl Kelsey, professor of epidemiology at Brown and corresponding author, but the new system relies on something far less ephemeral: DNA. Its use of hardy strands of genetic material allows it to handle even archived samples where cells have lost their physical integrity.
All of a person's immune cells in fact, nearly all of their cells have exactly the same DNA, but what makes a kidney cell different from a brain cell or a T-cell distinct from a B-cell are chemical alterations known as epigenetic marks. Those cause a cell's genes to be expressed in the particular way that makes them different. One type of those alterations is methylation, and every kind of cell has its own methylation signature.
"Once you understand the unique and really immutable signature that directs the differentiation of the cell, then you can use that and you don't need the cell anymore," Kelsey said.
So the new test detects those methylation signatures in a blood sample and, with the help of sophisticated algorithms, counts up how many cells of each type are in the sample. In the experiments reported in the paper, Kelsey, lead author William Accomando, and colleagues counted up the following major immune cell types, or leukocytes: T-cells, B-cells, NK cells, monocytes, eosinophils, basophils, and neutrophils.
Based on their tests using fresh human blood samples from more than 80 donors, they report that their technique's accura
|Contact: David Orenstein|