Elevated serum levels of interleukin-1 receptor antagonist in polymyositis/dermatomyositis. A biologic marker of disease activity with a possible role in the lack of acute-phase protein response.
OBJECTIVE
To determine whether the lack of acute-phase protein (APP) response in numerous patients with polymyositis/dermatomyositis (PM/DM) is related to an imbalance between cytokines and cytokine inhibitors.


METHODS
Levels of C-reactive protein (CRP), interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF alpha), IL-6, IL-1 receptor antagonist (IL-1ra), TNF soluble receptor 55 kd (sTNFR 55 kd), and sTNFR 75 kd were tested in the serum of 15 patients with PM/DM, 14 patients with spondylarthropathies (SPA), and 12 healthy blood donors. Serum IL-1 beta, TNF alpha, IL-6, IL-1ra, sTNFR were measured by specific immunoassays.


RESULTS
Serum levels of CRP were lower in PM/DM patients than in SPA patients. Normal or slightly elevated CRP values were found in 10 of the 15 PM/DM patients, 7 of whom had active myositis. Serum IL-6 levels were significantly higher in SPA patients than in PM/DM patients, whereas serum IL-1ra and sTNFR levels were significantly higher in PM/DM than in SPA patients. IL-1ra levels were particularly elevated in patients with active myositis and decreased in response to treatment.


CONCLUSIONS
These differences in cytokine levels, particularly IL-1ra, between PM/DM and SPA patients are indicative of distinct pathogenic mechanisms. High levels of IL-1ra may account for the weak APP response in some PM/DM patients. Our results suggest that measurement of IL-1ra, together with clinical examination, may provide useful information for the followup of PM/DM patients.
Gabay
C
C
Hôpital Cantonal Universitaire de Genève, Geneva, Switzerland.
Gay-Croisier
F
F
Roux-Lombard
P
P
Meyer
O
O
Maineti
C
C
Guerne
P A
PA
Vischer
T
T
Dayer
J M
JM
D000328:Adult; D000368:Aged; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis; D002648:Child; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000097:blood; D003882:Dermatomyositis / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D017285:Polymyositis / Q000097:blood*; D017472:Receptors, Interleukin-1 / Q000032:analysis*; D018124:Receptors, Tumor Necrosis Factor / Q000032:analysis; D012995:Solubility; D013167:Spondylitis, Ankylosing / Q000097:blood; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
D016207:Cytokines; D015850:Interleukin-6; D017472:Receptors, Interleukin-1; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein