Interleukin-6 is produced during both murine and avian Eimeria infections

The production of interleukin-6 (IL-6) during Eimeria infection was investi gated in an attempt to gain a better understanding of the role of this mult i-functional cytokine in resistance to this parasite. IL-6 production was m easured in both chickens, in which the disease is of economic importance, a nd the better-characterised murine model system. Systemic and local IL-6 production in mice during E. vermiformis infection was investigated, in the relatively resistant BALB/c strain, and the relati vely susceptible C57 BL/6 strain, using a murine IL-6 ELISA and the 7TD1 as say. Enhanced systemic production of IL-6 in serum was seen in infected BAL B/c mice when compared to C57 BL/6 mice. This difference was also reflected in the draining lymph node of the site of infection, assessed by testing s upernatants from stimulated mesenteric lymph node cells taken from infected mice at different times post-infection. Production of chicken IL-6-like factor activity was investigated using a mu rine IL-6 7TD1 bioassay. The presence of substantial quantities of IL-6-lik e factor activity was detected in serum taken from some chickens infected w ith E. tenella during the course of primary infection and, in a separate ex periment, during the first few hours post-infection, a time when the pro-in flammatory capacity of IL-6 would influence the developing immune response. These results suggest that IL-6 is also important in the induction of immu ne effector responses to Eimeria infections in the chicken. (C) 2000 Elsevi er Science B.V, All rights reserved.