Antibodies against a peptide sequence located in the linker region of the HMG-1/2 box domains in sera from patients with juvenile rheumatoid arthritis.
OBJECTIVE
To extend our work on the mapping of B cell epitopes on nucleosomal high mobility group (HMG) proteins in the sera of patients with juvenile rheumatoid arthritis (JRA).


METHODS
Seventy-seven pauciarticular-onset JRA serum samples from antinuclear antibody (ANA)-positive patients and 42 polyarticular-onset JRA patient sera found to react with HMG-2 by immunoblotting were used in this study. To identify B cell epitopes on HMG-2, recombinant HMG-2 protein fragments were used in enzyme-linked immunosorbent assay (ELISA) and in competition ELISA experiments with a set of overlapping synthetic peptides. Fine epitope mapping was achieved by oligopeptide synthesis, followed by immunoblotting.


RESULTS
Pauciarticular, but not polyarticular, JRA patient sera were found to recognize a lysine-rich major epitope (KKGKKKDP), which is located in the linker region of the HMG box domains of the HMG-2 nonhistone chromosomal protein. No significant immunoreactions were observed in sera from ANA-negative JRA patients and in sera from children with nonrheumatic diseases, indicating that this epitope seems to be specific for pauciarticular-onset JRA.


CONCLUSIONS
In addition to our previous finding that JRA sera will react with a defined epitope on HMG-17, pauciarticular JRA patient sera were also found to recognize a defined epitope on the HMG-2 protein, thus suggesting the importance of this epitope in the etiology of JRA.
Jung
F
F
University of Heidelberg, Germany.
Neuer
G
G
Bautz
F A
FA
D000595:Amino Acid Sequence; D000906:Antibodies / Q000032:analysis*; D001171:Arthritis, Juvenile / Q000235:genetics / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D008040:Genetic Linkage; D006609:High Mobility Group Proteins / Q000235:genetics* / Q000276:immunology*; D006801:Humans; D015151:Immunoblotting; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology*
D000906:Antibodies; D000939:Epitopes; D006609:High Mobility Group Proteins; D010446:Peptide Fragments