Longitudinal fluctuation of antibodies to extractable nuclear antigens in systemic lupus erythematosus.
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).


CONCLUSIONS
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.
Faria
Alex Carvalho
AC
Rheumatology Division, Federal University of São Paulo, EPM-UNIFESP, São Paulo, Brazil.
Barcellos
Karin Spat Albino
KS
Andrade
Luis Eduardo Coelho
LE
D000974:Antibodies, Antinuclear / Q000097:blood*; D034961:Antigens, Nuclear / Q000276:immunology; D001324:Autoantigens / Q000276:immunology; D004247:DNA / Q000276:immunology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008180:Lupus Erythematosus, Systemic / Q000453:epidemiology* / Q000276:immunology*; D008297:Male; D012189:Retrospective Studies; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000276:immunology; D012261:Ribonucleoproteins / Q000276:immunology; D017411:Ribonucleoproteins, Small Nuclear / Q000276:immunology; D016036:Seroepidemiologic Studies; D055517:snRNP Core Proteins; D000097585:SS-B Antigen; D000099207:SS-A Antigen
D000974:Antibodies, Antinuclear; D034961:Antigens, Nuclear; D001324:Autoantigens; D004247:DNA; D017412:Ribonucleoprotein, U1 Small Nuclear; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins; D000097585:SS-B Antigen; D000099207:SS-A Antigen