Al-Soudi A, et al. - A sum of 35 proteinase 3-antineutrophil cytoplasmic antibodies-positive subjects with granulomatosis with polyangiitis (GPA) were analyzed by researchers to estimate if the presence of immunoglobulin G4-positive (IgG4⁺) B cells and plasma cells in peripheral blood could serve as disease activity parameter in GPA. They recorded a higher median qPCR score in active GPA as compared to in remission/low disease activity (LDA) (Mann-Whitney U test). It also exceeded other known disease activity parameters in detecting activity. They noticed that a cutoff qPCR score of 11.2% exactly distinguished active disease from remission/LDA. They found a correlation between qPCR test and the BVAS (remission). Overall, they concluded the IgG4:IgG RNA ratio in GPA as an accurate distinguishing factor for active disease from remission.