The clinical significance of iC3b neoantigen expression in plasma from patients with systemic lupus erythematosus.
We studied the expression of an iC3b neoantigen (iC3b-NEO) in plasma from patients with systemic lupus erythematosus (SLE), by using a monoclonal antibody specific for iC3b/C3dg/C3d, to investigate the activation of the third component of complement in SLE. The plasma iC3b-NEO level in 40 untreated patients with active SLE was significantly higher than that in 36 normal subjects (mean +/- SD 31.5 +/- 13.9 micrograms/ml versus 12.3 +/- 3.3 micrograms/ml; P less than 0.001). The plasma iC3b-NEO level was highly correlated with clinical disease activity (tau = 0.62, P less than 0.0001), and it was the parameter most closely correlated with renal histologic activity in lupus nephritis (tau = 0.52, P less than 0.0001). Also, patients with diffuse proliferative lupus nephritis had the highest levels of plasma iC3b-NEO among all World Health Organization classes of lupus nephritis (P less than 0.01). We conclude that the plasma iC3b-NEO level is strongly associated with clinical disease activity and renal histologic activity in patients with SLE, and that plasma iC3b-NEO may be a sensitive and useful measure of complement activation in SLE.
Negoro
N
N
First Department of Internal Medicine, Osaka City University Medical School, Japan.
Okamura
M
M
Takeda
T
T
Koda
S
S
Amatsu
K
K
Inoue
T
T
Curd
J G
JG
Kanayama
Y
Y
D000911:Antibodies, Monoclonal; D003167:Complement Activation; D003176:Complement C3 / Q000032:analysis; D003179:Complement C3b / Q000276:immunology*; D003181:Complement C4 / Q000032:analysis; D015941:Complement Hemolytic Activity Assay; D003165:Complement System Proteins / Q000032:analysis; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis / Q000276:immunology* / Q000473:pathology; D008181:Lupus Nephritis / Q000276:immunology; D011863:Radioimmunoassay; D014461:Ultracentrifugation
D000911:Antibodies, Monoclonal; D003176:Complement C3; D003181:Complement C4; D003179:Complement C3b; D003165:Complement System Proteins