Enhanced H2O2 release from immune chicken leucocytes following infection with Eimeria tenella.

Cell-mediated immunity is thought to be important in the resistance of chickens to infection by coccidia, and it has been demonstrated that sporozoites of Eimeria tenella are very sensitive to superoxide ions. Therefore an investigation into the cellular responses in naive specific pathogen-free and hyperimmune birds was carried out with particular attention to their ability to produce reactive derivatives of oxygen. Leucocytes were isolated from the blood, spleen and caecal mucosa of chickens infected with E. tenella and assessed for their ability to release H2O2. Leucocytes obtained from the blood and spleen of hyperimmune birds 1 day after challenge showed an elevated ability to produce reactive oxygen intermediates. In contrast, the ability of leucocytes from naive chickens to produce these molecules was transiently depressed after challenge. Prior to challenge, mucosal leucocytes from immune chickens were also able to release heightened levels of H2O2 when compared with cells from naive chickens.