Systemic and mucosal immune responses of pigs to parenteral immunization with a pepsin-digested Serpulina hyodysenteriae bacterin

Serpulina hyodysenteriae infection of pigs, swine dysentery, causes a mucoh emorrhagic diarrhoea resulting in significant economic losses to swine prod ucers. The pathogenesis of this disease is poorly understood. Regardless, c ommercial vaccines have been developed and are in use. Thus, the present st udy was designed to examine cellular immune responses induced by parenteral S. hyodysenteriae vaccination. Significant antigen-specific interferon-gam ma (IFN-gamma) and blastogenic responses were detected from peripheral bloo d lymphocytes isolated from vaccinated pigs. However, poor IFN-gamma respon ses were detected from colonic lymph node lymphocytes from these same pigs despite significant antigen-specific blastogenic responses. In addition, pe ripheral blood IFN-gamma responses were diminished by either in vitro deple tion of CD4 expressing cells or by in vitro treatment with porcine IL-10. C olonic lymph node IFN-gamma responses were not inhibited by treatment with porcine IL-10. Vaccination also resulted in increased percentages of both m ucosal and peripheral blood CD8 single positive cells with concurrent decre ases in percentages of CD4 single positive cells as compared to percentages of these same populations from non-vaccinated pigs. In conclusion, these s tudies show that parenteral S. hyodysenteriae vaccination results in cellul ar immune responses detectable both peripherally (systemic immunity) as wel l as at the site of infection (mucosal immunity). However, it appears that regulatory mechanisms affecting IFN-gamma production in response to S. hyod ysenteriae antigen differ between peripheral and colonic compartments. (C) 1999 Elsevier Science B.V. All rights reserved.