title: No evidence of epitope spreading after immunization with the major Sm epitope P-P-G-M-R-P-P anchored to sequential oligopeptide carriers (SOCs).
abstract: The sequence Pro-Pro-Gly-Meth-Arg-Pro-Pro (PPGMRPP) is the major B-cell epitope of the Sm autoantigen. The aim of the present study was to evaluate the immune response against the native forms of Sm and U1RNP and immune mediated tissue injury after immunization with the sequence PPGMRPP anchored in five copies to a new type helicoid sequential oligopeptide carrier (SOC) formed by the repetitive Lys-Aib-Gly moiety, [(PPGMRPP)(5)SOC(5)]. Rabbits (n=3) were immunized with 0.5 mg of (PPGMRPP)(5)SOC(5)in complete Freud's adjuvant and boosted at days 26, 53, 99; control rabbits were immunized with the PPGMRPP alone (n=3), phosphate buffered saline (PBS) (n=1), SOC(5)alone (n=1), a peptide at aminoacid (aa) position 158-177 of myelin basic protein (MBP aa 158-147) (n=1) and three La/SSB autoantigen B-cell epitopes (n=3). Antibodies to (PPGMRPP)(5)SOC(5)were determined by enzyme linked immunosorbent assay (ELISA); precipitating anti-Sm and anti-U1RNP antibodies were detected by RNA precipitation and western blot on HeLa total cellular and nuclear extract and 12s sucrose gradient fraction of rat liver extracts. High titres of anti-(PPGMRPP)(5)SOC(5)antibodies not recognizing the native forms of Sm or U1RNP antigens were detected in the (PPGMRPP)(5)SOC(5)immunized but not in the control animals. The sera of two (PPGMRPP)(5)SOC(5)immunized but not of the control rabbits recognized a 67 kDa protein in HeLa nuclear extract, distinct from the 70 kDa U1RNP antigen. Diffuse and segmental increase of mesangeal matrix and cells, crescent formation, segmental glomerular necrosis, rarely massive subendothelial deposits occluding the lumen and C3 complement component in the mesangeal area were seen in the kidneys of one (PPGMRPP)(5)SOC(5)immunized, but not of the remaining animals. In conclusion, the immune response induced by (PPGMRPP)(5)SOC(5)was specific for the immunizing epitope but not for the native forms of Sm and U1RNP antigens, but it was associated with immune mediated kidney injury.
authors.affiliation: Department of Pathophysiology, Medical School, University of Athens, Greece. pvlah@dh.uoa.gr
authors.forename: P G
authors.initials: PG
authors.lastname: Vlachoyiannopoulos
authors.forename: C
authors.initials: C
authors.lastname: Petrovas
authors.forename: A G
authors.initials: AG
authors.lastname: Tzioufas
authors.forename: C
authors.initials: C
authors.lastname: Alexopoulos
authors.forename: V
authors.initials: V
authors.lastname: Tsikaris
authors.forename: A
authors.initials: A
authors.lastname: Guialis
authors.forename: L
authors.initials: L
authors.lastname: Nakopoulou
authors.forename: M
authors.initials: M
authors.lastname: Sakarellos-Daitsiotis
authors.forename: C
authors.initials: C
authors.lastname: Sakarellos
authors.forename: P
authors.initials: P
authors.lastname: Davaris
authors.forename: H M
authors.initials: HM
authors.lastname: Moutsopoulos
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000974:Antibodies, Antinuclear / Q000097:blood; D001324:Autoantigens / Q000008:administration & dosage* / Q000737:chemistry / Q000276:immunology; D001327:Autoimmune Diseases / Q000209:etiology / Q000276:immunology / Q000473:pathology; D015551:Autoimmunity; D000939:Epitopes / Q000008:administration & dosage* / Q000737:chemistry / Q000276:immunology; D005260:Female; D006367:HeLa Cells; D006801:Humans; D007114:Immunization / Q000009:adverse effects; D007668:Kidney / Q000276:immunology / Q000293:injuries / Q000473:pathology; D007674:Kidney Diseases / Q000209:etiology / Q000276:immunology / Q000473:pathology; D009842:Oligopeptides / Q000008:administration & dosage / Q000737:chemistry; D011817:Rabbits; D051381:Rats; D017411:Ribonucleoproteins, Small Nuclear / Q000008:administration & dosage* / Q000737:chemistry / Q000276:immunology; D055517:snRNP Core Proteins
chemical_list: D000974:Antibodies, Antinuclear; D001324:Autoantigens; D000939:Epitopes; D009842:Oligopeptides; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins