Mc. Garcia et al., Unique epitopes in RNA helicase II/Gu protein recognized by serum from a watermelon stomach patient, MOL IMMUNOL, 37(7), 2000, pp. 351-359
RNA helicase II/Gu (RH II/Gu) is a nucleolar antigen originally identified
using an autoimmune serum from a patient with watermelon stomach. A later r
eport showed that anti-RH II/Gu autoantibodies were also present at low fre
quency in connective tissue disease (CTD) patients who did not show any sym
ptoms suggestive of a watermelon stomach lesion. In an attempt to understan
d the relationship between watermelon stomach, also called gastric antral v
ascular ectasia (GAVE), and autoimmune disorder, we identified the antigeni
c sites recognized by these autoantibodies. Serum Gu uniquely recognized ep
itopes at amino acids 646-748 of RH II/Gu and all four CTD patient sera rec
ognized antigenic sites within amino acids 1-173. Anti-RH II/Gu serum produ
ced by immunizing rabbit with recombinant human RH II/Gu protein bound to t
he same antigenic sites recognized by the CTD patient sera, but it did not
recognize the serum Cu epitopes. Results are also presented showing the use
of these anti-RH II/Gu antibodies in the analysis of the evolutionary cons
ervation of RH II/Gu in human, monkey and mouse. (C) 2000 Elsevier Science
Ltd. All rights reserved.