- Interferon-gamma protects against chronic viral myocarditis by reducing mast cell degranulation, fibrosis, and the profibrotic cytokines transforming growth factor-beta 1, interleukin-1 beta, and interleukin-4 in the heart. Fairweather, D., Frisancho-Kiss, S., Yusung, S.A., Barrett, M.A., Davis, S.E., Gatewood, S.J., Njoku, D.B., Rose, N.R. Am. J. Pathol. (2004)