title: Biological effect of varying peptide binding affinity to the BoLA-DRB3*2703 allele.
abstract: MHC class I and II molecules are immunoregulatory cell surface glycoproteins, which selectively bind to and present antigenic peptides to T-lymphocytes. Murine and human studies show that variable peptide binding affinity to MHC II molecules influences Th1/Th2 responses by inducing distinctive cytokine expression. To examine the biological effects of peptide binding affinity to bovine MHC (BoLA), various self peptides (BoLA-DQ and fibrinogen fragments) and non-self peptides from ovalbumin (OVA), as well as VP2 and VP4 peptides from foot and mouth disease virus (FMD-V) were used to (1) determine binding affinities to the BoLA-DRB3*2703 allele, previously associated with mastitis susceptibility and (2) determine whether peptide binding affinity influences T-lymphocyte function. Peptide binding affinity was determined by a competitive assay using high affinity biotinylated self-peptide incubated with purified BoLA-DRB3*2703 in the presence of various concentrations of competing peptides. The concentrations of non-self peptide required to inhibit self-peptide binding by 50% (IC50) were variable, ranging from 26.92 to > 320 microM. Peptide-specific T-lymphocyte function was determined by measuring DNA synthesis, cell division, and IFN-gamma production in cultures of mononuclear cells from a BoLA-DRB3*2703 homozygous cow. When compared to non-stimulated control cultures, differences in lymphocyte function were observed for all of the assessed parameters; however, peptide-binding affinity did not always account for the observed differences in lymphocyte function.
authors.affiliation: Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Alizadeh
authors.forename: Niel
authors.initials: N
authors.lastname: Karrow
authors.forename: Bonnie A
authors.initials: BA
authors.lastname: Mallard
mesh_terms: D000483:Alleles; D000818:Animals; D001667:Binding, Competitive; D019921:Biotinylation; D015153:Blotting, Western; D002417:Cattle / Q000235:genetics* / Q000276:immunology*; D002455:Cell Division; D005452:Fluoresceins; D000949:Histocompatibility Antigens Class II / Q000235:genetics* / Q000378:metabolism*; D010047:Ovalbumin / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010455:Peptides / Q000235:genetics / Q000276:immunology; D011485:Protein Binding; D013388:Succinimides; D013601:T-Lymphocytes / Q000502:physiology
chemical_list: C087165:5-(6)-carboxyfluorescein diacetate succinimidyl ester; C423282:BoLA-DRB3 antigen; D005452:Fluoresceins; D000949:Histocompatibility Antigens Class II; C111390:OVA 323-339; D010446:Peptide Fragments; D010455:Peptides; D013388:Succinimides; D010047:Ovalbumin