Heterophil response to intraperitoneal challenge with invasion-deficient salmonella enteritidis and Salmonella-immune...

The present work compared the accumulation of intraperitoneal heterophils in day-of-hatch chicks following treatment with Salmonella enteritidis-immune lymphokine (ILK) and challenge with various strains of Salmonella enteritidis (SE). Day-of-hatch chicks received ILK by intraperitoneal injection and were challenged 1 hr later by intraperitoneal inoculation with one of the following SE strains: a wild-type, SE 890034-3; a delta cya-12 delta cyp-11 avirulent vaccine strain, chi 4357; and an invasion-deficient strain, InvA::kan, chi 4420. Four hours after challenge heterophils were recovered from the peritoneal cavity by lavage. The concentration of heterophils in the recovered lavage fluid was determined. Heterophil concentrations increased in response to challenge with each SE strain but there was a lower response to the invasion-deficient strain. The difference was statistically significant. This diminished heterophil response to challenge with invasion-deficient salmonellae supports existing evidence that the initial defensive reaction occurs at the earliest stages of the Salmonella-host interaction.