[Complement activation products (C3a and C5b-9) as markers of activity of dermatomyositis. Comparison with usual biochemical parameters].
BACKGROUND
Dermatomyositis (DM) is an autoimmune disease included in the group of idiopathic inflammatory myopathies. Markers of disease activity are needed for clinical control in order to facilitate adjustment of immunomodulatory therapy. We analyzed the relationship between complement activation products (CAP) and the activity of dermatomyositis and its usefulness in the follow-up of the disease and the prediction of recrudescences related to usual biochemical parameters.


METHODS
We studied 16 patients with DM that were followed periodically. In each appointment the degree of cutaneous and muscular activity was assessed and such disease activity was correlated with plasma levels of C3a and C5b-9, measured by ELISA.


RESULTS
Though we obtained certain correlation between disease activity and plasma levels of C3a and C5b-9, the strength of such correlation was not superior to that obtained by usual biochemical markers. C3a was shown to be the most sensitive marker (100 %) with a sufficient specificity (83.3 %) in the capability to predict recrudescences.


CONCLUSIONS
C3a and, to a lesser extent C5b-9, would be useful in the identification of patients with especially active DM as well as in predicting disease recrudescences. Nevertheless they are not superior to the rest of biochemical markers as indicators of current activity.
Campo
A
A
Servicio de Dermatología, Hospital Clínic, Barcelona, España. 29801acv@comb.es
Hausmann
G
G
Martí
R M
RM
Estrach
T
T
Grau
J M
JM
Porcel
J M
JM
Herrero
C
C
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D001798:Blood Proteins / Q000032:analysis; D003167:Complement Activation; D015926:Complement C3a / Q000032:analysis*; D015938:Complement Membrane Attack Complex / Q000032:analysis*; D003882:Dermatomyositis / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D012867:Skin / Q000473:pathology
D015415:Biomarkers; D001798:Blood Proteins; D015938:Complement Membrane Attack Complex; C047610:SC5b-9 protein complex; C044541:complement C3a, des-Arg-(77)-; D015926:Complement C3a