Submitted to: Veterinary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 18, 1998
Publication Date: N/A
Interpretive Summary: Baby chicks are very susceptible to salmonellae infections during the first 7 days after they hatch because their white blood cells cannot adequately ingest and kill the invading bacteria. Previous studies in our laboratory have dealt with methods to improve the baby chick's ability to fight off potential Salmonella infections. We have found newly hatched chicks can be protected from Salmonella infections by administration of a protein from white blood cells of older chickens. We isolated a particular white blood cell, heterophils, from the baby chicks treated with the protein. We then incubated these cells in a test tube with salmonellae. The results from these series of experiments showed heterophils from the baby chicks treated with the protein were able to ingest and kill greater numbers of salmonellae than those chicks not treated with the protein. These results are important to the poultry industry because we can stimulate a particular white blood cell to fight off Salmonella infections in young, susceptible chicks.
Technical Abstract: During the first week post-hatch, chickens demonstrate an increased susceptibility to infection by bacteria such as Salmonella. The purpose of the present study was to evaluate the effects of immune lymphokines on phagocytosis and killing activities of heterophils in chicks during the first 1-7 days of life. Lymphokines isolated from chicken splenic T cells harvested from Salmonella enteriditis (SE) hyperimmunized hens (SE-ILK), have in past experiments, demonstrated augmentation of heterophil activity in day-of-hatch chicks resulting in protection from SE organ invasion. The present work reveals significant increases (P<0.05) in heterophil phagocytosis and killing when comparing chicks treated with SE-ILK to control groups in vitro. In SE-ILK treated groups, a two-fold or greater increase is noted in heterophil phagocytosis within one hour of incubation as compared to controls. Heterophils isolated from 1-day-old and 4-day-old chicks treated with SE-ILK killed significantly greater numbers (p<0.05) of SE than heterophils isolated from control groups. By day 7 post-hatch, significance is not noted in the killing activity of heterophils from treated groups when compared to control groups. However, heterophils from SE-ILK groups continue to kill greater numbers of SE than control groups. This data supports SE-ILK augmentation results in enhanced heterophil function in chicks during the greatest period of susceptibility to Salmonella invasion. Interesting is the potential for application of heterophil augmentation against salmonellae infections in the hatchery before an anticipated or in the early stages of an outbreak to arrest or diminish the losses associated with invasion by pathogens.