Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/22/2008
Publication Date: 7/7/2008
Citation: Karcher, E.L., Beitz, D.C., Stabel, J.R. 2008. Cytokine Secretion in Periparturient dairy cows naturally infected with Mycobacterium avium subsp. paratuberculosis [abstract]. American Dairy Science Association.
Technical Abstract: Johne's disease, cause by Mycobacterium avium subsp. paratuberculosis (MAP), has a devastating impact on the dairy industry. Cows typically are infected as neonates, and stressors, such as parturition, may induce the transition from the subclinical to a more clinical stage of disease. The objective of this study was to characterize cytokine secretion in periparturient dairy cows naturally infected with MAP. Twenty-five Holstein cows were classified according to infection status into three groups consisting of 8 noninfected healthy cows, 10 subclinical cows, and 7 clinical cows. Peripheral blood mononuclear cells (PBMCs) were isolated and cultured at 1.4 x 10**6 cells/mL with either medium alone (nonstimulated, NS), concanavalin A (ConA), or MAP whole cell sonicate (MPS). Culture supernatants were removed and analyzed by ELISA to detect the secretion of IFN-gamma, IL-4, IL-10, and TGF-beta. Production of IFN-gamma by MPS-stimulated PBMCs was greater (P < 0.01) in subclinical cows compared with control cows and tended to be greater (P < 0.11) than in clinical cows. Similarly, when PBMCs were stimulated with either ConA or MPS, IL-10 secretion was greater (P < 0.04) in subclinical cows compared with controls. In contrast, secretion of IL-4 by MPS-stimulated PBMCS was greater in clinical cows compared with control (P <0.004) and subclinical cows (P <0.04). There was a tendency for NS PBMCs from infected cows to have increased secretion of TGF-beta compared with the control, but secretion of TGF-beta by ConA and MPS-stimulated PBMCs was not affected by infection group. Parturition evoked significant effects on cytokine secretion with observed increases in IFN-gamma, IL-10, IL-4, and TGF-beta, depending upon infection status of the cows and the in vitro stimulant used. Results of this study indicate that in dairy cows the secretion of many key cytokines is modulated by natural infection with MAP and by the periparturient period.