High prevalence of autoantibodies to RNA helicase A in Mexican patients with systemic lupus erythematosus.
BACKGROUND
Autoantibodies to RNA helicase A (RHA) were reported as a new serological marker of systemic lupus erythematosus (SLE) associated with early stage of the disease. Anti-RHA and other autoantibodies in Mexican SLE patients and their correlation with clinical and immunological features were examined.


METHODS
Autoantibodies in sera from 62 Mexican SLE patients were tested by immunoprecipitation of 35S-labeled K562 cell extract and enzyme-linked immunosorbent assay (anti-U1RNP/Sm, ribosomal P, beta2GPI, and dsDNA). Anti-RHA was screened based on the immunoprecipitation of the 140-kDa protein, the identity of which was verified by Western blot using rabbit anti-RHA serum. Clinical and immunological characteristics of anti-RHA-positive patients were analyzed.


RESULTS
Anti-RHA was detected in 23% (14/62) of patients, a prevalence higher than that of anti-Sm (13%, 8/62). Prevalence and levels of various autoantibodies were not clearly different between anti-RHA (+) vs. (-) cases, although there was a trend of higher levels of anti-RHA antibodies in patients without anti-U1RNP/Sm (P = 0.07). Both anti-RHA and -Sm were common in cases within one year of diagnosis; however, the prevalence and levels of anti-RHA in patients years after diagnosis did not reduce dramatically, unlike a previous report in American patients. This suggests that the high prevalence of anti-RHA in Mexican patients may be due to relatively stable production of anti-RHA.


CONCLUSIONS
Anti-RHA was detected at high prevalence in Mexican SLE patients. Detection of anti-RHA in races in which anti-Sm is not common should be clinically useful. Racial difference in the clinical significance of anti-RHA should be clarified in future studies.
Vázquez-Del Mercado
Monica
M
Departamento de Biología Molecular y Genómica, Instituto de Investigación en Reumatología y del Sistema Músculo Esquelético, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Sierra Mojada 950, Guadalajara, Jalisco, CP 44340, México. dravme@hotmail.com
Palafox-Sánchez
Claudia A
CA
Muñoz-Valle
Jose F
JF
Orozco-Barocio
Gerardo
G
Oregon-Romero
Edith
E
Navarro-Hernández
Rosa E
RE
Salazar-Páramo
Mario
M
Armendariz-Borunda
Juan
J
Gámez-Nava
Jorge I
JI
Gonzalez-Lopez
Laura
L
Chan
Jason Yf
JY
Chan
Edward Kl
EK
Satoh
Minoru
M
D000328:Adult; D017668:Age of Onset; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D001324:Autoantigens / Q000276:immunology; D015153:Blotting, Western; D053487:DEAD-box RNA Helicases / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D047468:Immunoprecipitation; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000276:immunology*; D008800:Mexico; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000276:immunology*; D015995:Prevalence; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D001323:Autoantibodies; D001324:Autoantigens; D009363:Neoplasm Proteins; C098487:DHX9 protein, human; D053487:DEAD-box RNA Helicases