Autoantibodies to RNA helicase A: a new serologic marker of early lupus.
OBJECTIVE
To investigate the clinical and immunologic significance of autoantibodies to RNA helicase A (RHA) in patients with systemic rheumatic diseases.


METHODS
The study group comprised 1,119 individuals enrolled in the University of Florida Center for Autoimmune Diseases registry from 2000 to 2005. Diagnoses were based on standard criteria. Autoantibodies were analyzed by immunoprecipitation and Western blot assays.


RESULTS
Anti-RHA was observed in 17 (6.2%) of 276 patients with systemic lupus erythematosus (SLE), 2 patients with antiphospholipid antibodies, and 3 other patients, but anti-RHA was not observed in any patient with polymyositis/dermatomyositis, systemic sclerosis, rheumatoid arthritis, or Sjögren's syndrome. Anti-RHA was present in only 2.9% of African American patients, compared with 6.0% of white patients and 12-25% of patients of other races; this was in striking contrast to the frequency of anti-Sm in African American patients (27.2%). Among patients with SLE, anti-RHA was common in young patients (26% of those whose initial visit was at an age younger than 20 years versus 3-4% of those who were initially seen at ages 20-49 years) and at an early stage of disease (23% of those whose first clinic visit was within 1 year of disease onset versus 2-8% of those whose first visit was at least 1 year after disease onset). In 9 of 11 patients, levels of anti-RHA decreased to <10% of the initial value within 9-37 months, while levels of coexisting anti-Ro or anti-Su remained the same. New specificities developed in 2 patients (anti-nuclear RNP and anti-Sm, and anti-ribosomal P, respectively). These data suggest that the level of anti-RHA diminishes over time, and that anti-RHA is regulated via a mechanism different from that for other lupus-related autoantibodies.


CONCLUSIONS
Anti-RHA is a new serologic marker for SLE. It is produced mainly in young non-African Americans at an early stage of their disease. Anti-RHA has a unique tendency to diminish over time. The production of anti-RHA may depend on a process restricted to early SLE, or it may be highly sensitive to treatment.
Yamasaki
Yoshioki
Y
University of Florida, Gainesville, FL 32610, USA.
Narain
Sonali
S
Yoshida
Hideo
H
Hernandez
Liza
L
Barker
Tolga
T
Hahn
Paulette C
PC
Sobel
Eric S
ES
Segal
Mark S
MS
Richards
Hanno B
HB
Chan
Edward K L
EK
Reeves
Westley H
WH
Satoh
Minoru
M
D000328:Adult; D001741:Black or African American / Q000235:genetics; D000367:Age Factors; D000368:Aged; D000375:Aging; D001213:Asian / Q000235:genetics; D001323:Autoantibodies / Q000097:blood*; D001324:Autoantigens / Q000235:genetics / Q000276:immunology; D016022:Case-Control Studies; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000276:immunology*; D015971:Gene Expression Regulation, Enzymologic; D006630:Hispanic or Latino / Q000235:genetics; D006801:Humans; D007198:Indians, North American / Q000235:genetics; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000175:diagnosis* / Q000235:genetics / Q000276:immunology*; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000235:genetics / Q000276:immunology*; D012216:Rheumatic Diseases / Q000097:blood / Q000235:genetics / Q000276:immunology; D017411:Ribonucleoproteins, Small Nuclear / Q000235:genetics / Q000276:immunology; D013997:Time Factors; D044465:White People / Q000235:genetics; D055517:snRNP Core Proteins
D001323:Autoantibodies; D001324:Autoantigens; D009363:Neoplasm Proteins; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins; C098487:DHX9 protein, human; D053487:DEAD-box RNA Helicases