Background and aims The aim of this study was to investigate plasma ADAMTS-13 activity in proliferative lupus nephritis patients, and evaluate their correlations with clinical, laboratory and pathological features, especially the vascular lesions in lupus nephritis.

Methods Plasma samples from 163 biopsy-proven class III and IV lupus nephritis patients and 98 normal controls were collected. ADAMTS-13 activity was evaluated by residual collagen binding assay. IgG autoantibodies against ADAMTS-13 were detected by ELISA. Levels of vWF were evaluated by ELISA. Their associations with clinical, laboratory and pathological features were further assessed.

Results Plasma ADAMTS-13 activity in lupus nephritis patients was significantly lower than that in normal controls (84%±21% vs. 90%±13%, p=0.005). The plasma levels of vWF was significantly higher in lupus nephritis group than that in normal controls (1.00±0.79 vs. 0.70±0.30, p=0.025). Plamsa ADAMTS-13 activity was negatively correlated with the level of serum creatinine and proteinuria (r=−0.354, p<0.001; r=−0.200, p=0.011, respectively). Patients with higher ADAMTS-13 activity had significantly higher levels of factor H (401.51±183.01 µg/ml vs. 239.02±155.45 µg/ml, p=0.005). Plasma ADAMTS-13 activity was negatively associated with the total pathological AI scores ,acute glomerular vascular lesions, acute renal vascular lesions (all p<0.001) and tubular atrophy ( p=0.011). Low activity of ADAMTS-13 was a risk factor for renal outcomes (p=0.039, HR=0.047, 95% CI: 0.120–1.005).

Conclusions Decreased ADAMTS-13 activity was found in proliferative lupus nephritis patients and plasma ADAMTS-13 activity was closely associated with renal injury indices, especially pathological vascular scores. The role of ADAMTS-13 in the disease need to be further investigated.