Serum cytokine responses during acute human granulocytic ehrlichiosis

Human granulocytic ehrlichiosis (HGE) is caused by obligate intracellular bacteria in the Ehrlichia phagocytophila group. The disease ranges from subclinical to fatal. We speculated that cell-mediated immunity would be important for recovery from and potentially in the clinical manifestations of HGE; thus, serum tumor necrosis factor alpha (TNF-alpha), interleukin 1 beta (IL-1 beta), gamma interferon (IFN-gamma), IL-10, and IL-4 concentrations were studied, IFN-gamma (1,035 +/- 235 pg/ml [mean +/- standard error of the mean]) and IL-10 (118 +/- 46 pg/ml) concentrations were elevated in acute-phase sera versus convalescent sera and normal subjects (P less than or equal to 0.013 and P less than or equal to 0.018, respectively). TNF-alpha, IL-1 beta, and IL-4 levels were not elevated. Cytokine Levels in severely and mildly affected patients were not different. HGE leads to induction of IFN-gamma-dominated cell-mediated immunity associated with clinical manifestations, recovery from infection, or both.