ANCA and IgG subclasses.

We studied IgG subclass distribution of ANCA in 247 patients with ELISA. We used monoclonal subclass specific antibodies and purified MPO and proteinase 3 as antigen. We found that IgG1 and IgG4 yield high values in both groups. We also found that high IgG2 titers were rare among the anti-proteinase 3 positive, while it was common among anti-MPO sera. In the assays for IgG3 the situation was the opposite.