Autoantibodies in pediatric systemic lupus erythematosus: ethnic grouping, cluster analysis, and clinical correlations.
OBJECTIVE
(1) To evaluate the spectrum of serum autoantibodies in pediatric-onset systemic lupus erythematosus (pSLE) with a focus on ethnic differences; (2) using cluster analysis, to identify patients with similar autoantibody patterns and to determine their clinical associations.


METHODS
A single-center cohort study of all patients with newly diagnosed pSLE seen over an 8-year period was performed. Ethnicity, clinical, and serological data were prospectively collected from 156/169 patients (92%). The frequencies of 10 selected autoantibodies among ethnic groups were compared. Cluster analysis identified groups of patients with similar autoantibody profiles. Associations of these groups with clinical and laboratory features of pSLE were examined.


RESULTS
Among our 5 ethnic groups, there were differences only in the prevalence of anti-U1RNP and anti-Sm antibodies, which occurred more frequently in non-Caucasian patients (p < 0.0001, p < 0.01, respectively). Cluster analysis revealed 3 autoantibody clusters. Cluster 1 consisted of anti-dsDNA antibodies. Cluster 2 consisted of anti-dsDNA, antichromatin, antiribosomal P, anti-U1RNP, anti-Sm, anti-Ro and anti-La autoantibody. Cluster 3 consisted of anti-dsDNA, anti-RNP, and anti-Sm autoantibody. The highest proportion of Caucasians was in cluster 1 (p < 0.05), which was characterized by a mild disease with infrequent major organ involvement compared to cluster 2, which had the highest frequency of nephritis, renal failure, serositis, and hemolytic anemia, or cluster 3, which was characterized by frequent neuropsychiatric disease and nephritis.


CONCLUSIONS
We observed ethnic differences in autoantibody profiles in pSLE. Autoantibodies tended to cluster together and these clusters were associated with different clinical courses.
Jurencák
Roman
R
Division of Rheumatology, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8.
Fritzler
Marvin
M
Tyrrell
Pascal
P
Hiraki
Linda
L
Benseler
Susanne
S
Silverman
Earl
E
D000293:Adolescent; D000367:Age Factors; D001323:Autoantibodies / Q000032:analysis / Q000097:blood*; D002648:Child; D016000:Cluster Analysis; D015331:Cohort Studies; D004247:DNA / Q000276:immunology; D018450:Disease Progression; D005006:Ethnicity; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000208:ethnology / Q000276:immunology*; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D044469:Racial Groups; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000276:immunology; D012720:Severity of Illness Index; D044465:White People; D055517:snRNP Core Proteins / Q000276:immunology
D001323:Autoantibodies; D017412:Ribonucleoprotein, U1 Small Nuclear; D055517:snRNP Core Proteins; D004247:DNA