One of the immune system's soldiers, interferon-gamma, actually helps prevent tissue damage in mice given a condition similar to a heart-damaging autoimmune disease in humans, the scientists report in the Dec. 18 issue of the journal Circulation.

"In treating autoimmune disease," says Noel Rose, M.D., Ph.D., a professor of pathology at Hopkins, "it's possible that treatments that alter the immune system's overall function could make one autoimmune disease better but make a second one worse."

The scientists discovered interferon-gamma's protective role as they were trying to figure out how an immune soldier called interleukin-12 causes heart damage in this disease, known as myocarditis. Because interleukin-12 "recruits" interferon-gamma, increasing its presence in cells, the scientists suspected interferon-gamma might be involved in damaging tissue.

Unexpectedly, mice without normal interferon-gamma function had more heart damage, and mice treated with extra interferon-gamma had less damage than normal mice. Extra interferon-gamma prevented heart damage completely in seven of the 11 mice studied, says Rose, whose studies were funded by the National Institutes of Health.

"Scientists generally thought that interferon-gamma was responsible for many actions of interleukin-12, so it was surprising that the two proteins really have opposite effects in these mice," explains Marina Afanasyeva, M.D., M.P.H., a Ph.D. candidate in molecular microbiology and immunology at Johns Hopkins University's Bloomberg School of Public Health. "Interleukin-12 probably depends on interferon-gamma for its effects in some circumstances but not o
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Contact: Joanna Downer
jdowner1@jhmi.edu
410-614-5105
Johns Hopkins Medical Institutions
18-Dec-2001