Atypical antineutrophil antibodies in patients with ANCA-associated vasculitides

Aim

To evaluate the prevalence and clinical significance of anti-lysosome-associated membrane glycoprotein 2 antibodies (LAMP-2) in patients with ANCA-associated vasculitides (AAV).

Material and methods

We recruited 59 patients with newly diagnosed (n=35) or relapsing (n=24) AAV. Diagnosis was established according to the American College of Rheumatology criteria (1990) or Chapel-Hill Consensus Conference definition (2012). Only patients with BVAS v.3 of ≥3 were included. Thirty-six age- and sex-matched healthy controls comprised the control group. Concentration of anti- LAMP-2 antibodies was determined by ELISA.

Results

Using data from the control group, the upper reference level of anti-LAMP-2 antibodies was defined as a cutoff of 48.9 ng/ml. In patients with AAV, the median concentration of anti-LAMP-2 antibodies was significantly higher than in the control group: 42.1 [39.7; 45.9] ng/ml and 37.1 [35.7; 39.2]) ng/ml, respectively (p<0.001). However, only 6 of 59 patients (10.1%) tested positive for these antibodies. Median concentration of anti-LAMP-2 antibodies did not change significantly following achievement of remission (p=0.079). ANCA against proteinase-3 or myeloperoxidase were present in 89.8% of patients with AAV.

Conclusion

Anti-LAMP-2 antibodies should not be used for clinical evaluation of patients with AAV.

Key words

Antineutrophil cytoplasmic antibodies (ANCA), granulomatosis with polyangiitis, microscopic polyangiitis, vasculitis, lysosome-associated membrane glycoprotein 2.