Edward D. McGruder

In vivo activation of heterophil function in chickens following injection with Salmonella enteritidis-immune lymphokines.

We have previously shown that increased resistance to Salmonella enteritidis organ infectivity in day‐old chicks was conferred by the immunoprophylactic administration of S. enteritidis‐immunc lymphokines (ILK). This resistance was associated with a significant increase in the number of circulating heterophils 4 h after ILK injection. The objective of the present study was to evaluate heterophil function following the administration of ILK in day‐old chicks. Significant increases (P < 0.001) in adherence, chemotaxis, and phagocytosis of S. enteritidis were found with heterophils isolated from ILK‐injected chickens compared to the heterophils isolated from birds injected with either pyrogen‐free saline or lymphokines from non‐immune T cells. After phagocytosis, the heterophils from the ILK‐injected chickens were also able to kill significantly greater numbers of S. enteritidis more rapidly than did the heterophils from the saline‐injected control birds (within 30 min, control cells killed 21.89% of the bacteria whereas ILK‐treated cells killed 88.22%). We also found that the heterophils from the ILK‐injected birds were more efficient killers of S. typhimurium, S. gallinarum, and E. coli These results strongly suggest that the protection against S. enteritidis organ invasion induced by the prophylactic treatment of day‐old chicks with ILK involves activated heterophils which migrate rapidly to the inflammatory stimulus where they phagocytize and kill the bacteria. J. Leukoc. Biol. 57: 56–62; 1995.

Genus-Specific Detection of Salmonellae using the Polymerase Chain Reaction (PCR)

Oligonucleotide primers for the polymerase chain reaction (PCR) that enable genus-specific detection of members of the genus Salmonella were developed. The primers amplify a 496-bp genetic sequence of members of the genus Salmonella. Amplification of DNA extracted from all other genera of the family Enterobacteriaceae and various other gram-positive aerobic and anaerobic bacteria yielded negative results. Applications of the PCR using these genus-specific primers are discussed.

Comparison of Prophylactic and Therapeutic Efficacy of Salmonella enteritidis-immune Lymphokines against Salmonella enteritidis Organ Invasion in Neonatal Leghorn Chicks

Investigations in our laboratories have indicated that when Salmonella enteritidis (SE)-immune lymphokines--supernatants from concanavalin-A-stimulated T cells derived from SE-immune adult chickens--were administered intraperitoneally to 1-day-old chicks before SE challenge, they conferred protection against SE organ invasion within 24 hr. This resistance mediated by SE-immune lymphokines was associated with a concomitant increase in peripheral blood polymorphonuclear leukocytes that peaked 4 hr after SE challenge. In the present study, we evaluated efficacy of SE-immune lymphokines in protecting chicks against SE organ invasion and alterations in peripheral blood polymorphonuclear leukocyte counts. Administration of SE-immune lymphokines to chicks either 30 min or 6 days before SE challenge caused a significant reduction in SE organ invasion. However, when SE-immune lymphokines were administered 2 days after SE challenge, there was no reduction in SE organ invasion. Both prophylactic (before SE challenge) and therapeutic (after SE challenge) administration of SE-immune lymphokines caused a significant increase in numbers of peripheral blood polymorphonuclear leukocytes. Results from these studies suggest that SE-immune lymphokines have potential value as an effective prophylactic but not as a therapeutic modulator of early resistance to SE organ invasion in neonatal leghorn chicks.

Efficacy of Salmonella enteritidis (SE)-immune lymphokines from chickens and turkeys on SE liver invasion in one-day-old chicks and turkey poults.

We have shown previously that increased resistance to Salmonella enteritidis (SE) organ infectivity in 1-day-old chicks was conferred by the immunoprophylactic administration of SE-immune lymphokines (SEILK). These lymphokines have been found to be present in the cell culture media of concanavalin A-stimulated splenic lymphocytes obtained from SE-immunized chickens. In the present study we evaluated whether turkeys also produced SEILK and whether these lymphokines could protect 1-day-old chicks and turkey poults against SE liver invasion. In addition, we tested the ability of our original chicken SEILK to reduce SE liver invasion in turkey poults. Day-of-hatch chicks and turkey poults were injected intraperitoneally with immune lymphokines of either chicken or turkey origin. One hour later the birds were challenged per os with SE, and 20 hours later their livers were examined by bacteriological methods for the presence of SE. We found that SEILK induced from the splenic lymphocytes of SE-immunized turkeys reduced SE liver invasion in both chicks and turkey poults. Conversely, we also determined that SEILK produced by chicken splenic lymphocytes conferred protection against invasion by SE in turkey poults. This research is the first report of the production of SEILK in turkeys and also the first report on the cross-species activity of these effector molecules in chickens and turkeys.

Characterisation of colony-stimulating activity in the avian T cell-derived factor, Salmonella enteritidis-immune lymphokine.

This investigation was designed to characterise the specific cytokine activity from the conditioned medium of concanavalin A-stimulated avian T cells derived from Salmonella enteritidis-immune chickens, S enteritidis-immune lymphokine (ILK). Studies were designed to determine first, whether colony-stimulating activity was present in ILK, second, the type(s) of colonies from the bone marrow that were supported in vitro by the potential colony-stimulating factors in ILK and, third, whether colony-stimulating activity was present in serum from chicks treated with ILK and challenged with S enteritidis, and to use physicochemical treatment as a means of identifying the potential colony-stimulating factor(s) in ILK. Both ILK alone and serum from chicks treated with ILK and challenged with S enteritidis caused significant increases in the number of colony-forming units (CFU) from the bone marrow in vitro. After 10 days of incubation, ILK alone supported the in vitro growth of granulocytic bone marrow colonies. The colony-stimulating activity from serum derived from chicks treated with ILK and challenged with S enteritidis peaked two hours after the challenge. When ILK was either heated at 100 degrees C or treated with trypsin or acid and then injected into chicks, all the chicks responded with significant increases in circulating polymorphonuclear leucocytes (PMNs). However, when assayed for in vitro colony-stimulating activity, only trypsinisation destroyed the activity in ILK. The results indicate that a colony-stimulating factor which preferentially supported the growth of granulocytic bone marrow colonies was present in ILK and that the factor was stable to heat and acid but sensitive to trypsin.