Eosinophils are a key component of anti-parasite immune responses and also play a central role in allergies. During HES, however, the cells appear in large numbers even though an underlying cause for their production is not known. The disease mostly affects men. Steroids, hydroxyurea and alpha interferon have all been used to treat the disease, but often unsuccessfully. Even when those treatments do work, they often cause unwanted side effects.
In a letter appearing in this week's The Lancet, Gerald Gleich, M.D., and colleagues from the Mayo Clinic and Foundation in Rochester, Minn., describe how a drug used to treat a form of leukemia is remarkably successful at reducing eosinophil levels in people with HES. The drug, imatinib mesylate, reduced eosinophil levels to normal in four of five patients studied and completely eliminated their symptoms.
"It's a different world," says Dr. Gleich, who has since moved to the University of Utah. "The disease is gone as long as the patients continue to take their medication."
The only patient who did not respond to the drug had elevated levels of interleukin-5, or IL-5, a protein in the blood that helps promote the growth of eosinophils. It is therefore likely that the drug was unable to work because IL-5 was constantly triggering the cells to reproduce.
Imatinib mesylate inhibits several enzymes that help regulate a cell's growth and reproduction. Its
'"/>
Contact: Sam Perdue
sp189u@nih.gov
301-402-1663
NIH/National Institute of Allergy and Infectious Diseases
2-May-2002