Unmasking the Anti-La/SSB Response in Sera From Patients With Sjogren’s Syndrome by Specific Blocking of Anti-idiotypic Antibodies to La/SSB Antigenic Determinants

Abstract

Background: Autoantigen La/SSB is molecular target of humoral autoimmunity in patients with primary Sjogren's Syndrome (pSS) and systemic lupus erythematosus (SLE). In this study, we investigated the existence and possible influence of anti-idiotypic response to anti-La/SSB antibodies. Materials and Methods: Synthetic peptide analogs (pep) of the major antigenic determinants of La/SSB (289-308aa and 349-364aa) were prepared. Based on "molecular recognition" theory, complementary peptides (cpep), derived by anti-parallel readings of the noncoding strand of La/SSB DNA encoding for its antigenic determinants, were constructed. Sera from 150 patients with anti-La/SSB antibodies, 30 patients without anti-La/SSB antibodies, and 42 normal individuals were tested against all four peptides. F(abЈ) 2 fragments from anti-peptide IgG were prepared and F(abЈ) 2 -IgG interactions were evaluated using a specific anti-idiotypic ELISA. Results: All four peptides were recognized by anti-La positive sera (83% and 51% for pep and cpep 349-364 and 51% and 28% for pep and cpep289-308, respectively). Anti-cpep F(abЈ) 2 bound to a common idiotype (Id) located within or spatially close to the antigen combining site of anti La/SSB (anti-pep) antibodies. Homologous and crossinhibition experiments further confirmed this relation. The anti-idiotypic antibodies inhibited the anti-La/SSB antibody binding to recombinant La/SSB by 91%. To overcome the anti-idiotypic interference in anti-La/SSB detection, a specific assay was developed. Sera were heated for dissociation of Id-anti-Id complexes, anti-Id antibodies blocked with cpep, and anti-La/SSB reactivity was recovered. Application of this method to anti-Ro positive-anti-La/SSB "negative" sera showed that all anti-Ro/SSA positive autoimmune sera also possess anti-La/SSB antibodies. This reaction was not observed in 14 anti-Ro negative-anti-Sm/RNP positive sera from patients with SLE. Conclusions: Autoimmune sera from patients with pSS and SLE contain anti-idiotypic antibodies targeting a common anti-La/SSB idiotype. These antibodies can be detected using complementary peptides of La/SSB epitopes. The antiidiotypic antibodies mask the anti-La/SSB response. Hidden anti-La/SSB antibodies can be released and detected using complementary epitope analogs.

Role of idiotype–anti-idiotype interactions in the induction of collagen-induced arthritis in rats

“…The fact that RF is an antiidiotypic antibody in relation to anti-collagen autoantibodies, as well as the dependence of anti-collagen antibodies level from RF production level in arthritic and resistant rats, allow suggesting that rheumatoid factor and RF-producing lymphocytes are involved in regulation of anti-collagen autoreactive lymphocyte activity through IAI interactions. This does not contradict the contemporary knowledge of regulatory functions of anti-idiotypic antibodies and lymphocytes (Zanetti et al, 1991;Routsias et al, 2002;Wu et al, 2007;Calkins et al, 1990;Zhang, 2004). Therefore we do not exclude a direct activation of autoreactive anti-RCII lymphocytes by bovine collagen and can suppose that induction of anti-collagen autoreactive lymphocytes needs a Fig.…”

Possible therapeutic vaccines for canine myasthenia gravis: Implications for the human disease and associated fatigue

“…Indeed, naturally occurring anti-Id Ab against AChR Ab has been reported in 40% of human MG patients, and its presence is associated with lower anti-AChR Ab titers and clinical improvement (Dwyer et al, 1983;Dwyer et al, 1984). Furthermore, in other Ab-mediated autoimmune disorders, including systemic lupus erythematosus, Sjogren's syndrome and autoimmune necrotizing systemic vasculitis, anti-Id Ab that binds autoreactive Ab can be detected with the appropriate complementary/ARM peptides (Pendergraft et al, 2004;Routsias et al, 2002;Routsias et al, 2003). Thus, B cell vaccines of the type herein described may be useful in inducing or bolstering a natural and perhaps regulatory anti-Id Ab response in not only MG but other adult autoimmune diseases.…”

Analysis of parotid glands of primary Sjögren's syndrome patients using proteomic technology reveals altered autoantigen composition and novel antigenic targets

“…They also recognize recombinant La/SSB, but not recombinant Ro60 or Ro52 in enzyme-linked immunosorbent assays (ELISA) (data not shown). Moreover, previous studies from our laboratory have demonstrated the specific recognition of La/SSB by these autoantibodies [12].…”