Increased serum levels of B cell activating factor (BAFF) in subsets of patients with idiopathic inflammatory myopathies.
OBJECTIVE
To investigate serum levels of B cell activating factor (BAFF) in patients with myositis and correlate these to autoantibody profile, clinical phenotype and treatment.


METHODS
BAFF levels in sera from 49 patients with dermatomyositis, 44 with polymyositis, 6 with inclusion body myositis and 30 matched controls were measured by ELISA. Specific autoantibodies were detected by line blot and western blot assays.


RESULTS
Serum levels of BAFF were significantly higher in patients compared to healthy controls (p = 0.003). Patients with anti-Jo-1 autoantibodies had higher BAFF levels than control individuals (p<0.003) or patients without any specific autoantibodies (p<0.05). Patients with dermatomyositis had higher BAFF levels compared to polymyositis (p<0.05). Patients with interstitial lung disease (ILD) had higher BAFF levels than patients without ILD (p<0.05) or controls (p<0.01) but this could be explained by presence of anti-Jo-1 autoantibodies. BAFF levels correlated with serum creatine kinase (CK) (rs = 0.365, p = 0.0005) but not with C-reactive protein (CRP) levels. A negative correlation of BAFF levels with glucocorticoid daily dose for all patients (rs = -0.292, p = 0.003) and with cumulative glucocorticoid doses in early myositis cases (rs = -0.659, p<0.001) was recorded.


CONCLUSIONS
Our finding of elevated serum levels of BAFF in patients with myositis with described phenotypes together with the correlations between levels of BAFF and CK and a negative correlation with dose of glucocorticoids, indicate that BAFF could be a potential therapeutic target in such cases.
Krystufková
O
O
Institute of Rheumatology, Prague, Czech Republic. krys@revma.cz
Vallerskog
T
T
Helmers
S Barbasso
SB
Mann
H
H
Putová
I
I
Belácek
J
J
Malmström
V
V
Trollmo
C
C
Vencovsky
J
J
Lundberg
I E
IE
D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D000974:Antibodies, Antinuclear / Q000097:blood; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D053264:B-Cell Activating Factor / Q000097:blood*; D002097:C-Reactive Protein / Q000032:analysis; D016022:Case-Control Studies; D002648:Child; D003402:Creatine Kinase / Q000097:blood; D003882:Dermatomyositis / Q000097:blood / Q000188:drug therapy / Q000276:immunology; D005260:Female; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D009220:Myositis / Q000097:blood* / Q000188:drug therapy / Q000276:immunology; D017285:Polymyositis / Q000097:blood / Q000188:drug therapy / Q000276:immunology; D018709:Statistics, Nonparametric; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13 / Q000097:blood; D055815:Young Adult
D000974:Antibodies, Antinuclear; D001323:Autoantibodies; D053264:B-Cell Activating Factor; D005938:Glucocorticoids; C046750:Jo-1 antibody; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13; D002097:C-Reactive Protein; D003402:Creatine Kinase