Enhancement of phagocytosis and bacterial killing by heterophils from neonatal chicks after administration of Salmonella enteritidis-immune lymphokines

During the first week post-hatch, chickens demonstrate an increased suscept ibility to infection by bacteria such as Salmonella. The purpose of the pre sent study was to evaluate the effects of immune lymphokines on phagocytosi s 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 expe riments, demonstrated augmentation of heterophil activity in day-of-hatch c hicks resulting in protection from SE organ invasion. The present experimen ts reveal significant increases (p < 0.05) in heterophil phagocytosis and k illing 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 hete rophil phagocytosis within 1h of incubation as compared to controls. Hetero phils isolated from 1-day-old and 4-day-old chicks treated with SE-ILK kill ed 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 contr ol groups. However, heterophils from SE-ILK groups continue to kill greater numbers of SE than control groups. These data support SE-ILK augmentation results in an enhanced heterophil function in chicks during the greatest pe riod of susceptibility to Salmonella invasion. (C) 1999 Elsevier Science B. V. All rights reserved.