[Antibodies to proteinase-3 and myeloperoxidase in systemic vasculitis]

To investigate occurrence and diagnostic significance of antibodies to proteinase-3 (aPR-3) and myeloperoxidase (aMPO) in systemic vasculitis (SV).

A total of 98 patients with different forms of SV were examined: nonspecific aortoarteritis (NAA, n = 18), nodular polyarteritis (NP, n = 18), Wegener granulomatosis (WG, n = 20), obliterating thrombangiitis (OT, n = 21), and hemorrhagic vasculitis (HV, n = 21). Eight patients with primary antiphospholipid syndrome (PAPS) and 20 donors comprised a control group. aPR-3 and aMPO were detected by solid-phase enzyme immunoassay using kits ORGenTec Diagnostica GmbH.

aPR-3 were detected in 1 (5.6%) patient with NP and in 3 (14.3%) patients with HV. aPR-3 were detected in 13 (65%) of 20 patients with WG being significantly more frequent not only vs controls (0%) but in some forms of SV and PAPS (p < 0.05). Mean aPR-3 level in 13 WG patients was significantly higher than in 4 patients (1 with NP and 3 with HV) the sera of whom also contained aPR-3. 84.6% patients with WG had higher concentrations of aPR-3, this is significantly more frequently than in the comparison group. In NP and HV these autoantibodies were encountered in the serum only in moderate or low concentrations in patients with high clinicolaboratory activity of the disease. In WG patients there was no correlation between aPR-3 presence, form of the disease and basic clinical manifestations, but mean values of index of clinical activity of vasculitis were significantly higher in patients with aPR-3 than in those free of them. Concentration of aPR-3 in an active phase of the disease was significantly higher than in patients in remission. Moreover, aPR-3 were detected in 83.3% cases in active vasculitis and in 37.5% patients without it. Detection of aPR-3 in WG group was associated with mean sensitivity and good specificity. In examination of the patients in an active phase specificity rose but sensitivity fell. Optimal results were obtained in estimation of aPR-3 level. Thus, in moderate or high concentration, aPR-3 have good sensitivity and high specificity for diagnosis of WG, in a high titer (> 15 U/ml) they are highly sensitive and specific for this vasculitis. aMPO were detected in 1 of 18 patients with NP, in 1 of 21--with OT, in 3 of 21--with HV and in 2 of 21--with NAA. None patients with WG or PAPS had aMPO. aMPO were detected in NP and HV in high activity of inflammation. Part of the patients had affected kidneys.

Thus, WG is characterized by the presence and high concentration of aPR-3. In the latter case aPR-3 have high (100%) sensitivity and specificity for diagnosis of WG. Detection of aPR-3 can be used as an additional laboratory test for diagnosis of WG and estimation of its activity.