Background: Brucellosis is a highly contagious zoonotic disease between humans and animals known for high frequency of relapsing and ability to cause chronic infection. The function of immune system plays an important role in induction of chronic diseases. However, the role of immune system response is not completely studied. Therefore, this study designed to investigate the cytokine profile of the patients suffering from chronic and acute brucellosis.

 Materials and Methods: This descriptive- analytical study was performed on 22 patients with acute brucellosis (mean age 38±17), 21 patients with chronic brucellosis (mean age 43±10) and 21 healthy people (mean age 26±4) with the same age and sex as patients. The serum IFN-&gamma, IL-17, IL-5 and TGF- &beta levels were measured using ELISA method.

 Results: The mean IFN-&gamma serum level in acute and chronic brucellosis patients group was significantly higher than control group (p=0.045). The mean IL-17 serum level in acute brucellosis patients was significant decreased once compared with control group and in chronic patients was significantly decreased when compared with control group (p=0.024). In addition, the mean IL-5 and TGF-&beta serum levels of acute brucellosis patients group were significantly decreased as compared to chronic patients (p=0.001).

 Conclusion: The results of current study indicate that cytokine profile of chronic brucellosis patients is more related to Th2 immune response. Hence, Th2 immune response inhibition would be an appropriate way to treat and prevent disease to become chronic.