Experiments on mice have shown that mast cells help decrease skin damage over time from sun exposure or from poison oak, say the researchers.
The findings, to be published Sept. 2 in the online version of Nature Immunology, reveal that, in mice, mast cells help decrease skin damage over time from sun exposure or from poison oak.
"These reactions are much worse if mast cells aren't present," Nature Immunology quoted senior author Dr. Stephen Galli, professor and chair of pathology, as saying.
He said that the findings raised possibilities for the treatment of such problems, and that the results contradicted mast cells' reputation for being the trigger-happy gunslinger in an allergic reaction.
Galli's team exposed the ears of mice to either cycles of ultraviolet radiation or to urushoil, the irritating oil of poison oak. About a week later, mice genetically lacking mast cells showed much more inflammation than normal mice, and developed skin ulcers. Injections of mast cells helped reduce the ear swelling and prevent the ulceration.
"All you have to do to cure the mice of this problem is put the mast cells back in," Galli said. The researchers said that the ear swelling was limited by the immune-suppressing molecule the cells secreted, known as interleukin-10. They also identified which antibodies activated the mast cell receptors to trigger IL-10's release.
Trial injections of IL-10 have reduced inflammation in patients suffering from rheumatoid arthritis and psoriasis, with mixed results.
The researchers now plan to conduct further studies to look into whether mast cells reduce the development of skin tumours, such as melanoma or carcinomas, from longer term ultraviolet exposure. They will also investigate what other molecules contribute to suppressing the inflammation.
"You can't explain all of the anti-inflammatory aspects of mast cells with IL-10," Galli said.