title: Hydrophobic IgG-containing immune complexes in the plasma of autoimmune MRL/lpr mice, lactate dehydrogenase-elevating virus-infected mice, and pigs: association with transforming growth factor-beta and pH-dependent amplification.
abstract: Persistent infection of mice with lactate dehydrogenase-elevating virus (LDV) is associated with polyclonal B cell activation, autoimmunity, and circulating hydrophobic IgG-containing immune complexes (ICs), which bind to the surfaces of uncoated ELISA plates in the presence of 0.05% Tween 20. We demonstrate here that hydrophobic IgG-containing ICs also appear naturally in the plasma of autoimmune MRL/lpr mice. These and the similar hydrophobic ICs of LDV-infected mice as well as pigs coincide on ELISA plate surfaces with TGF-beta, apparently in the form of an IgG-TGF-beta complex. Circulating hydrophobic IgG-containing ICs are also susceptible to considerable amplification in vitro by exposure to alkaline conditions. By this latter method, the fraction of in vivo hydrophobic IgG, relative to the maximum in vitro chemically inducible IgG, was found to be about 20% in the plasma of LDV-infected mice, 5% in normal mouse plasma, and less than about 2% in pig plasma. These results indicate the potential for both chemically induced and protein-binding contributions to the generation of hydrophobic IgG-containing molecules, and have implications for immunopathological mechanisms in autoimmunity and persistent virus infections.
authors.affiliation: Department of Basic Biomedical Sciences, University of South Dakota School of Medicine, Vermillion, South Dakota 57069, USA.
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Zitterkopf
authors.forename: Quentin A
authors.initials: QA
authors.lastname: Jones
authors.forename: David S
authors.initials: DS
authors.lastname: Bradley
authors.forename: Kelly
authors.initials: K
authors.lastname: Durick
authors.forename: Raymond R
authors.initials: RR
authors.lastname: Rowland
authors.forename: Peter G W
authors.initials: PG
authors.lastname: Plagemann
authors.forename: William A
authors.initials: WA
authors.lastname: Cafruny
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex / Q000097:blood*; D018174:Arterivirus Infections / Q000276:immunology* / Q000821:virology; D015551:Autoimmunity; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007074:Immunoglobulin G / Q000097:blood*; D007772:Lactate dehydrogenase-elevating virus / Q000276:immunology*; D051379:Mice; D019463:Mice, Inbred MRL lpr; D013552:Swine; D016212:Transforming Growth Factor beta / Q000097:blood*
chemical_list: D000936:Antigen-Antibody Complex; D007074:Immunoglobulin G; D016212:Transforming Growth Factor beta