Submitted to: ARS Immunology Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 12/4/2003
Publication Date: 12/4/2003
Citation: Nonnecke, B.J., Foote, M.R., Miller, B.L., Fowler, M.A., Waters, W.R. 2003. Comparison of the adaptive immune response in neonatal and young adult dairy cattle utilizing a mycobacterium bovis bcg sensitization/ppdb challenge model [abstract]. ARS Immunology Workshop. Paper No. 70:63.
Technical Abstract: Acquisition and modulation of immune competency in calves during the neonatal and postnatal period are not well described. The purpose of this study was to characterize age-related changes in the functional capacities of peripheral blood mononuclear cell (PBMC) and neutrophil populations from antigen-sensitized calves. Milk replacer-fed Holstein bull calves were nonvaccinated (n = 6, vaccination controls) or vaccinated subQ (n = 6) with an attenuated strain of Mycobacterium bovis [bacille Calmette Guerin (BCG)] at 1 and 7 wk of age. Yearling heifers (n=4, adult controls) were vaccinated and sampled concurrently with the calves. Functional capacities of PBMC (i.e. mitogen and antigen-induced DNA-synthesis, T cell subset proliferation, cytokine and NO production, IgG secretion) and neutrophil (iodination and cytochrome C reduction) populations collected at 0 (pre-vaccination), 2, 5, 6 (boosted), 7, 8 and 11 wk were evaluated in vitro. The phenotype of PBMC populations was characterized by flow cytometry. The responsiveness of PBMC from nonvaccinated and vaccinated calves to polyclonal stimulation frequently was lower than adult PBMC. Responses of PBMC from vaccinated calves to recall antigen (PPDb) were evident at >2 wk (3 wk of age) after primary vaccination. With the exception of antigen-induced DNA synthesis, most functions (T cell subset proliferation, TNF-alpha, IFN-gamma and NO secretion) of PBMC from vaccinated calves were comparable to or exceeded those of vaccinated adults. Changes in cervical skin-fold thickness after intradermal administration of PPD (wk 11) were significant and comparable in vaccinated calves and adults confirming the development of a robust cell-mediated immune response in vaccinated calves. In contrast, antigen-specific IgG responses (i.e. PPD-specific IgG in sera and supernatants from PPD-stimulated cultures) of vaccinated calves were minimal or nonexistent relative to adult responses suggesting the contribution of the B cell to the immune response is limited in young cattle. Nonvaccinated calves did not respond to recall antigen in vivo (i.e. cutaneous delayed-type hypersensitivity) or in vitro. Neutrophil functions were affected by age but not vaccination.