Objective To compare the characteristics of two types of plasma component separators with different pore size (EC-30W pore diameter = 0.02 μm, EC-40W pore diameter = 0.03 μm) in the desensitization of ABO-incompatible kidney transplantation (ABOi-KT).

Methods The clinical data of ABOi-KT recipients desensitized by double filtration plasmapheresis (DFPP) in the department of renal transplantation of the First Affiliated Hospital of University of Science and Technology of China were retrospectively analyzed. The ABOi-KT recipients were divided into the 30W group (n = 25) and 40W group (n = 21) according to the type of secondary filtration membrane adopted. The DFPP-related parameters, changes in ABO blood group antibody titers and postoperative serum creatinine levels between two groups were compared, and the changes in plasma macromolecular substance concentrations before and after the first DFPP in the two groups of recipients were analyzed.

Results A total of 115 DFPP sessions were performed in two groups, and no serious complications occurred. There was no significant difference in the frequency of DFPP and plasma processing volume between two groups (P ＞ 0.05). The amount of plasma discarded in the first DFPP, dosage of albumin and transmembrane pressure of the secondary membrane in the 30W group were significantly higher than those in the 40W group (P ＜ 0.01). There was no statistically significant difference in the plasma concentration of albumin between two groups after the first DFPP (P ＞ 0.05), while the plasma concentrations of prealbumin, IgG and IgM molecules decreased significantly. The decrease rates in the 30W group were 21.18% ± 6.15%, 55.39% ± 4.13% and 73.41% ± 8.55%, respectively, and which in the 40w group were 14.87% ± 4.53%, 34.20% ± 4.88% and 74.66% ± 6.66%%, respectively. The pre-stored ABO blood group antibodies in two groups were successfully cleared to the safety standard (Both IgM and IgG titers were ≤1 : 8). No serious complications occurred after the operation, and the recipients were discharged with good transplant renal function. There was no statistically significant difference in the serum creatinine level between two groups after 1 month of operation (P ＞ 0.05).

Conclusions Both secondary filtration membranes with different pore sizes can selectively remove macromolecular substances. Selecting the secondary filtration membrane based on the molecular weight of the target molecule can optimize the removal effect and medical cost of DFPP. For ABOi-KT recipients with ABO blood group antibodies mainly of IgM type, pretreatment using large-pore secondary filtration membranes is safe and feasible.