Dynamics of a protective avian inflammatory response: the role of an IL-8-like cytokine in the recruitment of heterophils to the site of organ invasion by Salmonella enteritidis.

Increased resistance to Salmonella enteritidis (SE) organ infectivity in chickens can be conferred by the prophylactic administration of SE-immune lymphokines (ILK). Resistance is associated with an enhanced heterophilic accumulation within 4 h of ILK injection. In these studies, the role of IL-8 in ILK-mediated heterophil recruitment during SE infections in young chickens was investigated. Heterophil accumulation was enhanced 2-4 h after the i.p. injection of both ILK and SE (ILK/SE) when compared to the control chicks. An i.p. injection of a rabbit polyclonal anti-human IL-8 antibody significantly (P < 0.01) reduced the accumulation of heterophils in the peritoneum after the injection of ILK/SE. Injections of preimmune rabbit IgG had no effect on peritoneal heterophil numbers. Within 2 h of injection of ILK/SE, a ten-fold increase in heterophil chemotactic activity was found in the peritoneal lavage fluid from these chicks compared to the saline control chicks. Pretreatment, with the anti-IL-8 antibody, of the peritoneal lavage fluids collected from the ILK/SE-treated chicks dramatically reduced this heterophil chemotactic activity. Treatment of the lavage fluids from all groups with preimmune IgG had no effect on heterophil chemotaxis. Additionally, pretreatment of ILK with the anti-human IL-8 antibody had no effect on heterophil chemotaxis. The results from these experiments suggest that IL-8 is produced locally by the host in response to both the SE infection and the ILK. With these studies, it was established that IL-8 is a major chemotactic factor produced by the host, which aids in mediating the ILK/SE-induced recruitment of heterophils to the site of SE invasion.