ONTOGENY OF THE PHAGOCYTIC AND BACTERICIDAL ACTIVITIES OF TURKEY HETEROPHILS AND THEIR POTENTIATION BY SALMONELLA ENTERITIDIS-IMMUNE LYMPHOKINES

Heterophils, the functional equivalent to the mammalian neutrophil, ar e important mediators of natural resistance against invasive pathogens in poultry. Young poultry are susceptible to pathogens, such as Salmo nella enteritidis, during the first week post-hatch. No studies have e valuated the ontogeny of heterophil function in turkeys during the fir st few weeks post-hatch. Previous studies from our laboratory have sho wn day-old poults were protected against S. enteritidis organ invasion following immunoprophylactic administration of chicken S. enteritids immune lymphokines. Therefore, the objective in the present study was to characterize the development of phagocytosis and bacterial killing by turkey heterophils during the first 3 weeks of life and to compare the effect of immune lymphokines on the development of heterophil phag ocytosis and killing during the first 3 weeks post-hatch. Both functio nal phagocytosis and killing activities were age-dependent events. Dur ing the first 1-7 days post-hatch, little functional activity was demo nstrated which apparently is associated with susceptibility. Optimal h eterophil phagocytosis and killing activities were reached 14-21 days post-hatch. Administrating immune lymphokines significantly potentiate d phagocytosis (P < 0.01) and killing (P < 0.001) by turkey heterophil s. In fact, immune lymphokine administration to 1-7-day-old poults aug mented phagocytosis and killing activities of heterophils equivalent t o levels found in functionally mature 14-21-day-old poults. These resu lts demonstrate the ontogeny of the functional activity of the turkey heterophil is an administration of immune lymphokines significantly po tentiated the functional activity of the heterophil from poults during the first 3 weeks of life. Most importantly the administration of imm une lymphokines enhanced the functional activity of heterophils from 1 -7-day-old poults to levels comparable to that of an immunologically m ature bird.