Increased serum levels of interferon-γ and interleukin-12 during human brucellosis

Brucellosis is a zoonotic disease that often becomes chronic with a high rate of recurrence. To understand the cytokines induced during this infection we determined the levels of interleukin (IL)-1 beta, IL-2, LL-4, IL-8, IL-12, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in serum of patients with brucellosis and compared with those without brucellosis and controls. Control sera were taken from healthy persons residing in an area that was not endemic for brucellosis. The levels of IL-1, IL-2, IL-4, and TNF-alpha were not detectable in all the sera from patients. There was no difference in the level of IL-8 in patients with brucellosis and those without this disease. However, IL-8 was significantly higher in these two groups of patients compared with the controls. Significantly higher levels of IL-12 and IFN-gamma were found in the serum of patients with brucellosis compared with patients without brucellosis and controls. These data indicate that there is induction of Th1 type cytokines during human brucellosis.