Efficacy of plasmapheresis and semi-selective immunoadsorption for removal of anti-HLA antibodies

Background In organ transplantation, apheresis is frequently used for removal of anti-HLA antibodies. However, it is unclear whether plasmapheresis (PP) or semi-selective immunoadsorption (IA) should be employed, and the optimal number of apheresis sessions required to reach post-treatment objectives is also unknown. Methods We enrolled 43 patients from Bordeaux University Hospital who were treated with PP (n = 29) or IA (n = 14) for antibody-mediated rejection or pre-transplant desensitization. Using Luminex single-antigen flow beads, we assessed the initial mean fluorescence intensity (MFI) of 1416 positive beads with MFIs obtained after 7 to 8 apheresis sessions (extended protocol) and, if a serum was available, after the first four sessions (short protocol). Results MFI reduction after extended apheresis protocol was stronger with IA [87% (61%-100%)] than with PP [73% (22%-100%)] (P < .001). Indeed, 59% of the beads had a final MFI < 2000 with IA, whereas only 38% with PP (P < .001). The efficacy of removal depended on initial MFI but not on HLA specificity. A short protocol of apheresis showed excellent results without superiority of IA over PP for antibodies with an initial MFI < 3000. For antibodies showing MFI >= 2000 after four sessions, the residual MFI predicted the effectiveness of four additional sessions. Conclusion Monitoring the MFI of anti-HLA antibodies before and during apheresis protocol can guide physicians in the selection of apheresis technique and the number of sessions to be performed.

Automated summary

This study compared the efficacy of PP and IA in removing anti-HLA antibodies, and found that IA had a stronger MFI reduction than PP in the extended apheresis protocol. For antibodies with an initial MFI < 3000, there was no superiority of IA over PP in the short protocol. Residual MFI predicted the effectiveness of four additional sessions for antibodies with an initial MFI >= 2000.