title: An attempt to induce "Graves' disease of the gonads" by immunizing mice with the luteinizing hormone receptor provides insight into breaking tolerance to self-antigens.
abstract: BACKGROUND
  Gonadotropin receptors, unlike the thyrotropin receptor (TSHR), are not cleaved into disulfide-linked A- and B-subunits, nor do they shed A-subunits. Heavily glycosylated TSHR A-subunits initiate or amplify responses leading to stimulating TSHR-autoantibodies and Graves' hyperthyroidism.
  
  
  METHODS
  To investigate the possibility that mice immunized with luteinizing hormone receptor (LHR) would develop functional antibodies, we constructed adenoviruses expressing the rat-LH holoreceptor (LHR-Ad) and an LHR A-subunit equivalent (LHR-289-Ad). Female BALB/c mice were immunized with high doses (10(11) particles) of LHR-Ad, LHR-289-Ad, or control (Con)-Ad. Sera were tested using LHR-expressing eukaryotic cells for antibody binding by flow cytometry and for bioactivity by measuring cyclic adenosine monophosphate (cAMP) stimulation.
  
  
  RESULTS
  Elevated serum binding to LHR cells in some LHR-Ad and LHR-289-Ad immunized mice was not specific for LHR-expressing cells. Moreover, sera lacked bioactivity, consistent with unchanged serum estradiol and ovary histology. The difference between rat and mouse LHR-ectodomains is relatively small (3% at the amino-acid level). In contrast, despite amino-acid identity, immunization of mice with adenovirus expressing membrane-bound mouse thyroid peroxidase (TPO), but not soluble mouse TPO ectodomain, elicited strong TPO-specific antibodies.
  
  
  CONCLUSIONS
  Our investigations provide insight into antibody responses to self-antigens. First, antibodies are induced to large self-antigens like mouse-TPO when membrane bound. Second, lesser amino acid homology between the immunogen and mouse protein (91% vs. 97% for the human-TSHR and rat-LHR, respectively) favors antibody induction. Finally, from previous studies demonstrating the immunogenicity of the highly glycosylated human TSHR A-subunit versus our present data for the nonimmunogenic less glycosylated rat LHR, we suggest that the extent of glycosylation contributes to breaking self-tolerance.
authors.affiliation: Thyroid Autoimmune Disease Unit, Cedars-Sinai Research Institute and UCLA School of Medicine, Los Angeles, California 90048, USA.
authors.forename: Chun-Rong
authors.initials: CR
authors.lastname: Chen
authors.forename: Holly A
authors.initials: HA
authors.lastname: Aliesky
authors.forename: Basil
authors.initials: B
authors.lastname: Rapoport
authors.forename: Sandra M
authors.initials: SM
authors.lastname: McLachlan
mesh_terms: D000818:Animals; D001323:Autoantibodies / Q000096:biosynthesis / Q000276:immunology; D016466:CHO Cells; D019556:COS Cells; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D006031:Glycosylation; D006111:Graves Disease / Q000276:immunology*; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D051381:Rats; D011974:Receptors, LH / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D011974:Receptors, LH; C056626:thyroid microsomal antibodies