INTERLEUKIN-6 ACTIVITY IN DOGS WITH JUVENILE POLYARTERITIS SYNDROME -EFFECT OF CORTICOSTEROIDS

Juvenile polyarteritis syndrome (JPS) is an idiopathic febrile disease in dogs. Elevated serum levels of interleukin-g (IL-6) and tumor necr osis factor-alpha (TNF-alpha) have been reported in human patients wit h vasculitis. We investigated whether these cytokines are also elevate d in serum of dogs with JPS using sensitive bioassays. Increased level s of IL-6 activity were detected in the serum of 12 acutely ill dogs, whereas the IL-6 activity decreased to low or undetectable levels duri ng convalescence. Treatment of 5 acute JPS dogs with prednisone result ed in a rapid clinical improvement accompanied by a decrease of IL-6 a ctivity, Withdrawal of prednisone treatment caused reappearance of cli nical symptoms and high serum IL-6 activity within a few days. TNF act ivity could not be detected in the samples of normal dogs, convalescen t JPS, or acute JPS dogs. These studies support a role for IL-6 in the pathogenesis of JPS. (C) 1995 Academic Press, Inc.