Clinical relevance and HLA association of autoantibodies against the nucleolus organizer region (NOR-90).
OBJECTIVE
NOR-90 autoantibodies directed against the nucleolus organizer region (NOR) have been described as rare scleroderma associated antibodies. We studied the clinical features of patients with NOR-90 antibodies as well as their HLA phenotype.


METHODS
NOR-90 antibodies were detected by indirect immunofluorescence assay using HEp-2 cells, by chromosome spreads as a substrate and in addition by Western blot analysis with HeLa-S3 nucleolar extract. HLA antigens of the NOR-90 antibody positive patients were typed with the standard NIH complement dependent microcytotoxicity test.


RESULTS
Nine sera selected by means of the indirect immunofluorescence revealed a typical double band pattern of about 90 kDa identical with the pattern of 2 NOR-90 reference sera by Western blot analysis. Only one patient positive for NOR-90 antibodies suffered from systemic sclerosis (limited cutaneous scleroderma). The other patients with NOR-90 antibodies showed no signs of systemic sclerosis. All patients with NOR-90 antibodies were women and 8 of 9 patients (89 versus 13% of healthy controls, Pcorr < 0.001) were positive for the HLA-DR1 allele.


CONCLUSIONS
In contrast to the first report on NOR-90 antibodies we demonstrated no association of these antibodies with systemic sclerosis; however, we found strong evidence for an immunogenetic background of NOR-90 antibody formation.
Dick
T
T
Rheumaklinik und Rheumaforschungsinstitut, Aachen, Germany.
Mierau
R
R
Sternfeld
R
R
Weiner
E M
EM
Genth
E
E
D000328:Adult; D000368:Aged; D000974:Antibodies, Antinuclear / Q000097:blood*; D000918:Antibody Specificity; D015153:Blotting, Western; D004268:DNA-Binding Proteins / Q000276:immunology*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D008875:Middle Aged; D009697:Nucleolus Organizer Region / Q000276:immunology*; D035463:Pol1 Transcription Initiation Complex Proteins; D012216:Rheumatic Diseases / Q000276:immunology; D012595:Scleroderma, Systemic / Q000097:blood / Q000276:immunology*; D014157:Transcription Factors / Q000276:immunology*
D000974:Antibodies, Antinuclear; D004268:DNA-Binding Proteins; D035463:Pol1 Transcription Initiation Complex Proteins; D014157:Transcription Factors; C063844:transcription factor UBF