Dynamics of avian inflammatory response to Salmonella-immune lymphokines. Changes in avian blood leukocyte populations.

Investigations in our laboratories have indicated that an increased resistance to SE organ infectivity in chicks was conferred by the immunoprophylactic administration of SE-immune lymphokines (SE-ILK). This resistance was associated with an increase in the lamina propria thickness due to a marked infiltration of inflammatory polymorphonuclear cells (PMNs). In the present study, we determined whether the hematological profile of SE-ILK-treated chicks might reflect changes that are associated with the protection against organ invasion by SE. As protection has been observed in previous studies within 24 h of SE-ILK administration, we evaluated alterations in the circulating leukocyte profile in 1-day-old Leghorn chicks during this time period. We also determined whether the alterations in the peripheral blood leukocytes correlated with the increased protection against SE organ invasion induced by the SE-ILK. Within 4 h after an intraperitoneal injection of SE-ILK and challenge with SE, the number of circulating leukocytes increased significantly (P < 0.05) from all of the other treatment groups. The number of circulating PMNs was found to account for more than 80% of the increase in the number of circulating leukocytes. Using correlation analysis, we found a strong association between the number of circulating PMNs and the protection induced by SE-ILK against SE organ invasion. These studies associate the expansion of the available pool of circulating PMNs and the expression of innate resistance to organ invasion by SE.