Evaluation of serum cytokine levels in recurrent airway obstruction

Recurrent airway obstruction (RAO) represents a serious health problem and is traditionally classified as an allergic disease, where contact with an antigen can induce clinical airway inflammation, bronchial hyper-responsiveness and reversible airway obstruction. Previous studies have demonstrated the presence of the Th2 response in the lungs of human patients with asthma and horses with heaves. These cells are involved in the production of cytokines which regulate the synthesis of immunoglobulins. 40 horses were evaluated: 30 horses with RAO and 10 healthy animals. The expression levels of interferon-alpha 1 (IFN-alpha(1)), interferon-gamma (IFN-gamma), interleukin-1 beta, (IL-1 beta), IL-2, IL-4, IL-13 and tumor necrosis factor alpha (TNF-alpha) were measured in the serum obtained from control and RAO-susceptible horses during crisis. In all the patients, serum cytokine levels were detected. Serum median IL-13 and IFN-gamma levels were significantly higher in RAO-affected horses than in the healthy group (p < 0.001). The serum median IFN-alpha(1), IL-1 beta, IL-2, IL-4, and TNF-a levels were similar in both groups. These results indicate a low variability of the levels of cytokines and a high frequency of their detection in serum samples from horses with RAO. Immune mechanisms involved in equine RAO are more complex than those defined by a simple Th1/Th2 dichotomy.