Abstract:

Abstract: Objective: Double filtration plasmapheresis (DFPP) was able to reduce special antibody of IgG class by removal of IgG in blood circulation. The aims of this study is to investigate the difference of descent rate between special antibody and IgG, and the ratio of antibody and IgG by DFPP. Methodlogy: Twenyy eight patients diagnosed as ANCA associated vasculitides and twenty patients as antiglomerular basement membrane (anti-GBM) antibodies nephritis were enrolled this study. They received average 2.6±0.9 sessions of DFPP, in which 28 patients finished their third therapy. Special antibody of anti-GBM and ANCA titer as well as immunoglobulin IgG were measured in blood sample before each DFPP therapy and waste plasma after therapy, calculating reduction ratio of special antibody and IgG after a single session of DFPP, and comparing the change in ratio of antibody and IgG in blood and waste plasma. The clinical features and outcomes after three mouths were also observed. Result: During each DFPP the reduction ratio of IgG was much higher than that of special antibody including anti-GBM and ANCA (34.9±17.2% vs. 52.1±11.3%, p<0.01), but that of two kinds antibody had no differendce (37.4±19.4% vs. 34.0±16.0%, P>0.05). The reduction ratio of each session also had no difference, no matter of antibody or IgG (31.8±14.3% vs 36.5±18.5% vs 39.5±18.5%; P>0.05 and 50.3±11.1% vs 47.4±10.2% vs 44.6±10.5%; P>0.05). The ratio of special antibody and IgG was much higher in blood sample after DFPP therapy than before (24.8±12.5 vs. 17.3±7.6,P<0.001), but the same with waste plasma (17.7±10.4 vs. 17.3±7.6,P<0.05). During the intervals of DFPP, IgG bounces much more than special antibody (the first interval 60.6±39.6% vs. 17.5±20.6%; the second interval 48.9±24.4% vs. 21.4±31.1%，P<0.001). Among patients with anti-GBM positive, serum creatinine, anti-GBM concentration and incidence of oliguria were much lower in the ones with better antibody descent rate (p=0.002，0.004 and 0.022). Conclusion: During sessions of DFPP, the change rates of pathogenic antibodies and IgG both of reduction and bounces showed a significant difference. The cause of this phenomenon should be elucidated in clinic studies.

Key words:  Double filtration plasmapheresis, Antiglomerular basement membrane antibodies , Anti-neutrophil cytoplasmic antibody, Immunoglobulin G