Submitted to: Journal of Leukocyte Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 27, 1997
Publication Date: N/A
Interpretive Summary: Poultry products have been shown to be contaminated with Salmonella and food safety has become a major concern to the industry. Salmonella enteritidis (SE) is only one of many different bacteria that can infect poultry. During an infection with SE, white blood cells move to the location where the bacteria have invaded the body. However, we do not know how the chicken's white blood cells find the bacteria in the body. Our tests have shown that some proteins on the white blood cells' surface help direct the cells to the bacteria. The results of these tests are significant to the poultry industry because knowing what proteins are involved will help us to develop a treatment to boost the immune system so that Salmonella infection of the baby chick can be reduced.
Technical Abstract: Chicken heterophils activated in vivo following the intraperitoneal (i.p.) administration of Salmonella enteritidis-immune T lymphokines (SE-ILK) have been implicated in the protection against SE organ invasion. SE-ILK induces a heterophilia and directly (or indirectly) activates the granulocytes. We examined the mechanism of adherence within the avian heterophil system using an in vitro bovine serum albumin (BSA) matrix in which adherence is primarily CD11/CD18 integrin mediated in mammalian systems. Activated heterophils displayed a 4-fold increase in receptor- mediated adherence in vitro to BSA-coated slides as compared to control heterophils from PBS-injected birds. The increased adherence of activated heterophils can be partially blocked by either anti-CD11b or anti-CD18 antibodies in a dose dependent manner. Fluorescence-activated cell scanning (FACS) analysis of the heterophils shows that both control and SE-ILK-activated heterophils collected at 4 hours post injection with SE- ILK or PBS display similar amounts of integrin CD39c on their surface. This integrin is constitutively expressed and is responsible for the in vitro adherence of both groups. However, antibodies to the CD11b/CD18 complex block only the adherence of SE-ILK-stimulated heterophils. Thus, the CD11b/CD18 heterodimer is apparently up regulated in response to the injected SE-ILK and play a major role in the adherence of activated heterophils. Our studies in chickens parallel human and mouse studies showing the importance of the beta-2 integrins in adherence of activated cells.