ANTIBODY EPITOPES PROBED BY IMMUNOSELECTED PHAGE-DISPLAY LIBRARY PEPTIDES IN MEMBERS OF A FAMILY WITH VARIOUS RHEUMATIC MANIFESTATIONS

Objective. The random peptide combinatorial phage library approach ove rcomes the problem of lack of structural information about the aetiolo gical agent or the antigen responsible for a given disease. Here, we u sed such a strategy to gain insight into the aetiology of rheumatoid a rthritis (RA). Methods. We analyzed the reactivity of serum antibodies from a family with various rheumatic manifestations against RA-immuno selected nanopeptides displayed on phage particles. Results and conclu sion. We found that within the same family, there was a difference in antibody reactivity against the peptides tested. The IgG isotype of th e peptide reactive antibodies indicated that the observed reactivities were not related to the presence of polyreactive IgM antibodies. Furt hermore, it is unlikely that the observed reactivity was due to rheuma toid factors (RF), since two patients who were positive for the immuno selected Pep3 peptide (LSSREPQAR) were RF negative. We also found that the serum of one patient with polyarthralgias also reacted with the s ame peptide bound by the RA serum which may suggest the implication of a common aetiological agent in the apparition of this antibody reacti vity. Finally, we noted that one patient with Sjogren's syndrome had a ntibodies to the RA peptide, which may indicate a potential relationsh ip between these two autoimmune diseases.