Wednesday, April 24, 2013

New type of white blood cell identified; may play role in eczema

Scientists have identified a new type of white blood cell found in the upper layers of the skin that can either trigger or shut down inflammation.

The research was carried out in mice, which are commonly used as models for the human immune system. There is no proof that the same cells exist in humans, but these results will certainly impel researchers to look for them. It is possible that the newly identified cells play a role in eczema.

The cell type, “group 2 innate lymphoid cells” (ILC2), protects mice against parasitic worms called helminths. In mice, the cells appear to be the main source of the signaling molecule IL-13, known to be important in type 2 immunity—the arm of the immune system that is over-active in allergic disease and eczema.

The scientists took video that showed ILC2 cells moving around in the skin and occasionally stopping to make physical contact with mast cells. Mast cells play an important role in the early stages of inflammation. They are suppressed by IL-13.

However, the researchers also introduced ILC2 cells into mice that had no B or T cells (the white blood cells responsible for much of the immune response). In these mice, stimulating ILC2 cells caused inflammation with symptoms that looked like eczema.

So it appears that ILC2 cells can increase or decrease inflammation, depending on the signaling molecules they secrete. Potentially, drugs might be discovered to control ILC2 cells in the skin and, through them, manage eczema.

The research was performed by a joint Australian/New Zealand/American team led by Wolfgang Weninger, a professor of dermatology at the University of Sydney. It was published in the journal Nature Immunology.

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