Natural hidden autoantibodies to tissue transglutaminase cross-react with fibrinogen.
BACKGROUND
Patients with celiac disease display autoantibodies against tissue transglutaminase (TG2), and the high sensitivity and specificity of these autoantibodies render them a reliable tool for diagnosis. However, we found that denatured sera from healthy persons also showed reactivity against TG2.


METHODS
To further examine the specificity of this phenomenon, sera of healthy individuals and celiac patients were denatured by heat or pH shift.


CONCLUSIONS
Denatured sera of all individuals showed autoantibodies against TG2 in ELISA that could be specifically inhibited by TG2, but the biological role of these autoantibodies remains unknown. The alpha fibrinogen precursor could be isolated as serum protein that reacts with TG2 antibodies and treated sera reacted with fibrinogen in Western blotting. Cross-reactivity of TG2 antibodies with fibrinogen and vice versa was observed.


CONCLUSIONS
We hypothesise that denaturation of sera reveals hidden autoantibodies against TG2, which might be normally masked by fibrinogen.
Zöller-Utz
Ingrid M
IM
Medical Clinic 1, University of Erlangen-Nuernberg, Erlangen, Germany.
Esslinger
Birgit
B
Schulze-Krebs
Anja
A
Dieterich
Walburga
W
D001323:Autoantibodies / Q000097:blood; D001667:Binding, Competitive; D002446:Celiac Disease / Q000097:blood / Q000175:diagnosis* / Q000276:immunology* / Q000503:physiopathology; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D005340:Fibrinogen / Q000276:immunology* / Q000378:metabolism; D019204:GTP-Binding Proteins; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007070:Immunoglobulin A / Q000097:blood; D011379:Prognosis; D011489:Protein Denaturation; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D012680:Sensitivity and Specificity; D011503:Transglutaminases / Q000276:immunology*
D001323:Autoantibodies; D007070:Immunoglobulin A; D005340:Fibrinogen; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins