"Allergy cells" can aggravate cancer and psoriasis

The body's mast cells are mainly associated with allergic reaction in the way they release histamine and other inflammatory substances.

However, researchers at Karolinska Institutet have now demonstrated how the mast cells can also contribute to diseases like psoriasis and cancer.

Mast cells are most known for their association with allergic reactions, as they act like microscopic "bombs" to trigger the release of a number of substances that give rise to the classic allergic symptoms, such as swelling, congestion and itching. The explosive reactions are activated when an allergen (such as pollen particles) binds to receptors on the surface of the mast cell, which then opens and secretes part of its contents.

In the past few years it has emerged that mast cells, which are a type of immune cell, are probably also involved in the development of a number of other diseases, like atopical eczema, psoriasis, and the Hodgkins lymphoma cancer type. These diseases are characterised by chronic inflammations and an increase in the number of mast cells. However, the mechanisms behind this are relatively unknown.

Associate professor Gunner Nilsson at Karolinska Institutet and his research group have now found a possible explanation for the link between mast cells and several non-allergic diseases. The study, which is presented online by The Journal of Clinical Investigation, shows that mast cells can be activated in a previously unknown way that might lead to chronic inflammation.

"These new findings contribute to our understanding of the part played by the mast cell in atopical eczema, psoriasis and Hodgkins Lymphoma," says Mr Nilsson. "We hope that our research will make it possible for scientists to develop new forms of therapy for the mast cell-related diseases."

The group discovered that the CD30 protein, which is found on the surface of the immune systems T-lymphocytes amongst other places, can stimulate mast cells to release proteins that regulate the recruitment of inflammatory cells. Since it is already known that levels of CD30 are higher in people with psoriasis or atopical eczema and with Hodgkins lymphoma, the results can explain how the mast cells are activated and how they aggravate inflammation in these diseases.