Interleukin-3 and interleukin-4 in childhood brucellosis

The Th1/Th2 cytokine balance seems to be involved in the susceptibility or resistance to Brucella infection, however the precise role of interleukins in human brucellosis has not been thoroughly explored. The serum levels of interleukin-3 (IL-3) and interleukin-4 (IL-4) were measured by enzyme-linked immunosorbent assay (Quantikines, R&D Systems) in five children hospitalized for brucellosis and in a control group comprising ten children who were residents of the same area. IL-4 levels were significantly increased during both the acute phase (p = 0.0036) and convalescence (p = 0.026) as compared to controls. IL-3 levels were mildly increased during the acute phase (p = 0.026) without any significant difference noted during convalescence (p = 0.271) as compared to controls. Both IL-3 and IL-4 levels were neither related to hemoglobin values, nor to red and white blood cell, neutrophil, lymphocyte and platelet counts. Serum IL-4 levels are increased in hospitalized children with symptomatic brucellosis, a finding suggestive of a Th2 response leading to severe infection.