Serum deoxyribonuclease activity and anti-nuclear antibodies in ankylosing
spondilitis during longterm infliximab therapy

Petrovich D.M., Kunder E.V.

Belarussian Medical Academy of Post-Graduate Education, Minsk, Belarus

During the dynamic observation of 53 patients with ankylosing spondylitis who received long-term therapy with infliximab, the presence of antinuclear antibodies (ANA) was evaluated and the deoxyribonuclease (DNAse) serum activity was determined initially and at the 30th week of observation in order to study the possibility of using the studied parameters as predictors of secondary resistance to infliximab.
Positive nuclear type ANA was determined initially in 3,77%, in the 30-week follow-up 37.21% patients were ANA seropositive. In the comparison group, ANA-positive results were not detected. The frequency of occurrence of ANA in AS was, at baseline, comparable to healthy individuals (p>0,05). The incidence of ANA at the 30th week of treatment was significantly higher than at baseline (p<0,0001).
At the 30th week of infliximab treatment ANA-positive patients showed a significantly higher level of DNAse serum activity than ANA-negative ones (p<0,0001). DNase serum activity correlates with ANA-positivity (r =0,65; p<0,0001) in patients with AS who are receiving infliximab for a long time. Detection of serum DNase activity level of 4 units or more on the 30th week of infliximab therapy allows predicting secondary resistance to infliximab at 54th week according to the criterion of achieving target levels of ASDAS CRP, which is the basis for the correction of the treatment.