Background Catalytic deoxyribonuclease (DNAse) autoantibodies have been demonstrated in patients with autoimmune and infectious diseases, but conclusive data about DNAse activity of antibodies in patients with spondyloarthritides (SpA) are lacking. Recently the assessment of catalytic serum activity is used for diagnosis of many diseases. The assessment of DNAse serum activity is not used for spondyloarthritides diagnosis. The aim of the study is to assess DNAse abzyme activity of polyclonal IgG and DNAse serum activity in patients with SpA for next elaboration of differentiation criteria for these diseases.
Objectives The 125 patients with peripheral SpA, 51 patients with axial SpA and 69 healthy persons were examined. All patients were fulfilled ASAS criteria for peripheral and axial SpA (1).
Methods The samples of sera and polyclonal IgG isolated from patients and healthy persons were investigated. IgG were purified from the sera by combined method of affinity chromatography on protein A column. The experiments, confirming that abzyme activity is the essential quality of polyclonal IgG, were performed. The methods for DNAse activity assessment relied upon rivanol capacity to form a clot with DNA reversely proportional to this acid depolymerisation on the action of DNAse.
Results The levels of serum DNAse activity in patients with peripheral SpA (Me 4,0 units (min 3,0 max 5,0) (lower quartile 3,0 upper quartile 4,0)) and axial SpA (Me 2,0 units (min 1,0 max 4,0) (lower quartile 1,0 upper quartile 2,0)) were significantly (p<0,001) higher than in controls (Me 0,0 units (min 0,0 max 1,5) (lower quartile 0,0 upper quartile 0,0)).
The levels of DNAse abzyme activity in patients with peripheral SpA (Me 3,5 units (min 3,0 max 5,0) (lower quartile 3,0 upper quartile 4,0)) and axial SpA (Me 1,50 units (min 0,0 max 2,0) (lower quartile 1,0 upper quartile 2,0)) were significantly (p<0,001) higher than in controls (Me 0,0 units (min 0,0 max 1,5) (lower quartile 0,0 upper quartile 0,0)).
The levels of DNAse serum and IgG activity in patients with peripheral SpA were substantially (p<0,01) higher than in patients with axial SpA.
We revealed that determination of elevated levels (3 and more units) of serum DNAse activity might be applied for discrimination of periferal and axial SpA (sensitivity 82,5% (95%Cl: 74,2-89,9), specificity 84,3% (95%Cl: 78,1-90,3), positive likelihood ratio (PLR) 6,12, negative likelihood ratio (NLR) 0,16)). The detection of elevated levels (3 and more units) of DNAse IgG activity might be implicated for discrimination of periferal and axial SpA (sensitivity 77,25% (95%CL: 69,5-86,2), specificity 92,3% (95%CL: 80,5-98,8), PLR 10,50, NLR 0,19)).
Conclusions We confirmed the presence of elevated levels of serum DNAse and DNAse polyclonal IgG activity in patients with peripheral and axial SpA in comparison with the health persons and prevalence of these activities in peripheral SpA. We proposed original tests for differentiation of peripheral and axial SpA on the basis of assessment of DNAse serum and abzyme activities.
Rudwaleit M. New classification criteria for spondyloarhritis. Int Adv J Rheumatol 2010;8:1-7.
Disclosure of Interest None Declared
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