Development Of A Cenp-A/Cenp-B-Specific Immune Response In A Patient With Systemic Sclerosis

Antibodies directed against an epitope motif on CENP-A have been shown to cross-react with mimotopes on other autoantigens and on Epstein-Barr nuclear antigen 1 (EBNA-1), suggesting a molecular mimicry. We describe here the gradual development of an anticentromere immune response in a patient with systemic sclerosis, which started from an antihistone response and was not mediated by molecular mimicry. Via an epitope on histone H3, the antibody response spread to a homologous epitope in the H3 homology domain of CENP-A. This was followed by an intramolecular epitope spreading to N-terminal peptides of CENP-A containing the known epitope motif G-P-X-1-R-X-2 From there it spread to corresponding epitopes on CENP-B and to mimotopes of the major CENP-A epitope motif on other autoantigens including EBNA-1. Whether the D-penicillamine treatment received by this patient was involved in the triggering of this cascade remains a matter of speculation.