Forty-two patients were evaluated for donor specific anti HLA sensitization before they recivied ABO incompatible kidney transplantation. Each recipient was evaluated by complement dependent cytotoxicity (CDC) crossmatch, flow crossmatch, single antigen bead assay (SAB) and lysate based solid phase crossmatch Desensitaztion.
The desensitization protocol for ABO incompatibile transplant at our centre includes infusion of 500 mg of Rituximab which is administered, 10 to 12 days prior to KT. 2 to 10 sessions of plasmapheresis depending on titer performed over 2 to 14 days before surgery until a recipient’s isoagglutinin titer decreased to a level below 1:8. Postoperative Plasmapheresis was performed only when the antiA,B isoagglutinin titer was above a level of 1:8 within first two weeks of transplant or patient has graft dysfunction with graft biopsy is suggestive of ABMR. All the ABO-i KT patients received induction therapy with either Basiliximab (an anti-CD25 monoclonal antibody) on the day of kidney transplant (KT). Plasmapheresis with IVIG infusions initiated from Day −10. During plasmapheresis, plasma is replaced with FFP and 5% Albumin. Immunosuppressants (Tacrolimus and MMF) were started 10 days prior to surgery. During the transplant surgery 500 mg of iv methylprednisolone is given. Titres of anti-A and/or Anti-B are monitored on daily basis with target levels being < 1:8 by serial tube dilution method on the day of transplant. Induction with Basiliximab (on day 0 and 4) is given in most patients. In high-risk patients, rabbit ATG was given in a total dose of 3–4.5 mg/kg on Day 0 and then alternate days post-transplant. One patient in the ABOi transplant cohort expired within 2 days of transplantation due to refractory septic shock, in the remaining 33, patient survival was 97% and graft survival was 95% at one year follow up period.
Antibody mediated rejection (ABMR) was seen in four (9.5%) out of 42 patients. In non sensitized group-A, ABMR was 2.5% and sensitized group ABMR was seen in 7.1% with DSA positivity. Graft loss within one month post-transplant was seen in 2 patients due to ABMR with positive DSA only in the sensitized group –B (p value is 0.06). Both these patients had flow CM negative but had SAB DSA and Lysate CM positive, with total MFI strength above 5000. Anti HLA DSA positivity with ABO- incompatibility is associated with poor graft survival if MFI is more than 5000.