Submitted to: Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2000
Publication Date: N/A
Interpretive Summary: Swine dysentery is a diarrheal disease of pigs which results in significant economic losses to swine producers. Although the organism that causes swine dysentery is known, how this disease develops in the large intestine is not well understood. Commercial vaccines have been developed for swine dysentery and are currently in use. A recently developed swine dysentery vaccine appears to provide better protection of pigs against dysentery tha previous vaccines, but how this vaccine works is unknown. The present study was designed to examine the in vitro responses of cells isolated from pigs following intramuscular vaccination with this recently developed vaccine. Stimulation of cells from vaccinated pigs resulted in increased percentages of a specific type of white blood cell. It is believed that this type of white blood cell, which is increased following vaccination, may play a role in protecting vaccinated pigs from swine dysentery. In conclusion, these studies show that intramuscular vaccination results in alterations in the immune response which may provide protection from swine dysentery.
Technical Abstract: A vaccine inducing protective immunity to a spirochetal-induced colitis of pigs predominately stimulates expansion of CD8**+ cells in vivo and in antigen-stimulated lymphocyte cultures. CD8**+ cells, however, are rarely considered necessary for protection against extracellular bacterial pathogens. In the present study, pigs recovering from colitis resulting from experimental infection with Brachyspira (Serpulina) hyodysenteriae ha increased percentages of peripheral blood CD4**-CD8**+ (alpha alpha- expressing) cells as compared to percentages from non-infected pigs. Kappa delta 8 alpha alpha**+ cells proliferated in antigen-stimulated cultures of peripheral blood mononuclear cells from B. hyodysenteriae-vaccinated pigs. Proliferating CD8 alpha alpha**+ cells consisted of CD4**-, CD4**+, and gamma delta TCR**+ cells. CD4**-CD8 alpha beta**+ cells from vaccinated or infected pigs did not proliferate upon in vitro antigen stimulation. Of the CD8 alpha alpha cells that had proliferated, flow cytometric analysis indicated that the majority of the CD4**+CD8**+ cells were large (i.e., lymphoblasts), whereas the CD4**-CD8**+ cells were predominately small. Addition of monoclonal antibodies (mAb) specific for either porcine MHC class I or class II antigens inhibited B. hyodysenteriae-specific proliferative responses, whereas addition of mAb to porcine MHC II, but not porcine MHC I, inhibited the CD8 alpha alpha response. In vitro depletion of CD4**+ cells by flow cytometric cell sorting diminished, but did not completely abrogate, the proliferative response of cells from vaccinated pigs to B. hyodysenteriae antigen stimulation. These results suggest that CD8 alpha alpha cells are involved in protective immunity to a spirochetal- induced colitis of pigs.