 |
|
|
 |
Longitudinal Fluctuation of Antibodies to Extractable Nuclear Antigens in Systemic Lupus
Erythematosus
ALEX CARVALHO FARIA, KARIN SPAT ALBINO BARCELLOS, and LUIS EDUARDO COELHO ANDRADE ABSTRACT. Objective. To examine the appearance, persistence, and disappearance of anti-extractable nuclear antigen (ENA, Sm, U1-RNP, Ro/SSA, and La/SSB) and anti-native DNA (dsDNA) antibodies during systemic lupus erythematosus (SLE) followup. Methods. One hundred and thirty patients who fulfilled American College of Rheumatology classification criteria for SLE with at least 5 yearly anti-ENA and dsDNA tests between 1987-2002 were retrospectively selected. Four longitudinal antibody data patterns were considered for each antibody: always absent, always present, absent at diagnosis with positive seroconversion, and present at diagnosis with negative seroconversion. Results. Antibodies to Ro/SSA were present in 47%, U1-RNP in 36%, DNA in 32%, Sm in 23%, and La/SSB in 7% of patients. Among patients ever positive for a given autoantibody, the frequency of the "always present" pattern was 52% for anti-Ro/SSA, 38% for U1-RNP, 17% for Sm, 11% for La/SSB, and 9% for DNA antibodies; the frequency of positive seroconversion was 56% for anti-La/SSB, 33% for DNA, 26% for Sm, 21% for U1-RNP, and 15% for Ro/SSA. Time to positive seroconversion varied from 1 to 8 years after diagnosis. Among patients with a positive test at diagnosis the frequency of those remaining positive between the 2nd and 4th year of followup decreased to 39-78%, depending upon autoantibody specificity; between the 5th and 10th years this rate was 20-75%. Antibody data pattern frequency differed significantly among autoantibody specificities except between anti-U1-RNP and Ro/SSA (p = 0.15) and between anti-DNA and Sm antibodies (p = 0.29). Conclusion. The high frequency of longitudinal fluctuation in anti-ENA antibodies suggests that a periodic reappraisal may be appropriate in seronegative patients with a suspect diagnosis of SLE. The clinical significance of such fluctuation deserves future study. (J Rheumatol 2005;32:1267-72) Key Indexing Terms:
SYSTEMIC LUPUS ERYTHEMATOSUS From the Rheumatology Division, Federal University of São Paulo, EPM-UNIFESP, São Paulo, Brazil. Supported in part by CAPES (Brazilian Agency for Research Development) and by the Research Funds of the Brazilian Society of Rheumatology. A.C. Faria, MD; K.S.A. Barcellos, BSc; L.E.C. Andrade, MD, PhD. Address reprint requests to Dr. L.E.C. Andrade, Rua Botucatu 740 3º andar, São Paulo, SP 04023-062, SP, Brazil. E-mail: luis@reumato.epm.br Accepted for publication February 20, 2005. |