Clinical Efficacy and Safety of Protein A Immunoadsorption In Desensitization Therapy for Highly Sensitized Renal Transplant Recipients: A Prospective Cohort Study

Aim: High-level pre-HLA antibodies (MFI ≥ 10,000) can increase the risk of acute rejection after kidney transplantation by more than three times. Traditional plasmapheresis has issues of loss of coagulation factors. This study evaluates the desensitization efficacy of protein A immunoadsorption (IA), a highly selective IgG removal technique, in patients with high sensitization.

Methods: Inclusion of 129 sensitized patients with high HLA-I and/or HLA-II antibodies (Luminex single antigen test MFI ≥ 8,000) from Xiangya Second Hospital in 2018-2024 , using a prospective single-arm design. Continuous IA treatment for 5-7 days, four times absorption each day, blood flow rate 100-150 mL/min, followed treatment with low-dose IVIG at 0.5g/kg after whole adsorption. Monitor DSA intensity, coagulation function, and the amount of anti-HLA antibodies eluted before and after adsorption. The control group consists of patients (N=20) from the historical cohort who received plasma exchange plus rituximab therapy.

Results: Regarding antibody clearance efficacy, in the IA group, the median MFI of HLA-I class antibodies IgG decreased by 72% (from 15,200 to 4,250, p=0.002), significantly higher than in the control group (decreased by 38%, p<0.01). The median MFI of HLA-II class antibodies IgG decreased by 12% (from 9,800 to 8,100, p=0.415), with no statistically significant difference. However, high-titer HLA-II as well as HLA-I antibodies were detected in both eluates.

In clinical outcome evaluation, the postoperative 6-month survival rate of the transplanted kidney in group IA was higher than that in the control group (93.8% vs. 75%, p<0.01), and eGFR improved within 6 months. The incidence of acute antibody-mediated rejection (ABMR) was lower than that in the control (12.5% vs. 35% , P<0.01). BK virus activation rate was no statistically significant difference (15.6% vs. 10%, p>0.05).

Conclusion: Protein A immunoadsorption can rapidly and effectively remove HLA-IgG antibodies, improving the transplant prognosis of highly sensitized patients, making it valuable for clinical application.