Human monoclonal thyroglobulin autoantibodies: epitopes and immunoglobulin genes.
Autoantibodies to thyroglobulin (TgAbs) are common markers of thyroid autoimmunity, but relatively few human monoclonal TgAbs have been described. From a panel of 64 human monoclonal TgAbs (isolated from a thyroid-disease derived combinatorial Ig gene library), we selected seven with unique genetic features for detailed characterization. These TgAbs preferentially recognize native (not denatured) Tg, like serum autoantibodies. Most have high affinities for Tg (dissociation constant 10(-10) to 10(-9) m). Their light (L) chain Ig genes are not unusual, but four of the five heavy (H) chain genes are new. Moreover, one H chain belongs to the small VH2 family, not previously reported for autoantibodies to Tg or thyroid peroxidase. The TgAbs inhibit the binding to Tg of the thyroid donor's serum autoantibodies, indicating epitopic overlap. Competition analysis (surface plasmon resonance) shows that the TgAbs recognize overlapping epitopes in an immunodominant region on the Tg dimer ( approximately 660 kDa). Two major and several minor epitopic regions were defined, each associated with a particular H + L chain combination. In conclusion, our TgAb panel provides novel information regarding the repertoire of H chain genes encoding human TgAbs as well as the relationship between the H chains and the epitopes recognized on this major thyroid autoantigen.
Autoimmune Disease Unit, Cedars-Sinai Research Institute and the University of California, Los Angeles School of Medicine, Los Angeles, California 90048, USA.
Francesco
F
Latrofa
Martin
M
Phillips
Basil
B
Rapoport
Sandra M
SM
McLachlan
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000235:genetics* / Q000276:immunology*; D000918:Antibody Specificity; D001323:Autoantibodies / Q000097:blood / Q000235:genetics* / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000276:immunology; D020349:Surface Plasmon Resonance; D013954:Thyroglobulin / Q000276:immunology
D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D000939:Epitopes; C006606:anti-thyroglobulin; D013954:Thyroglobulin