ABO-mismatched renal transplantation in children: a report of the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) and the Midwest Organ Bank (MOB).

Successful ABO-mismatched renal transplantation (RT) (blood group A2 donor to blood group B or O recipient) has occurred in adults in the setting of a low titer (< or =4) natural isoagglutinin (anti-A) level in the recipient of the mismatched organ. Similar experiences have rarely occurred in children. Between 1986-1996, 11 pediatric patients (6 male and 5 female) received 11 ABO-mismatched kidneys [7 cadaveric (CAD) and 4 living related donor (LRD)]. There were 8 O recipients/A2 donor pairs, 2 B recipients/A2 donor pairs and 1 B recipient/A2B donor pair. Recipient age at the time of RT was 14.7+/-3.0 yr (mean +/- SD). Prior to RT, 2 recipients underwent splenectomy and none received donor-specific transfusions. Induction and early maintenance immunosuppression consisted of corticosteroids (11 pts), ALG/ATG (6 pts), OKT3 (3 pts), azathioprine (11 pts) and cyclosporine (8 pts). The mean 30-d cyclosporine dosage was 10.6+/-4.0 mg/kg/d. Eight patients suffered > or =1 acute rejection episodes, the initial episode occurring within the first 31 d post-transplant in 7 of them. Five grafts (45.4%) failed secondary to vascular thrombosis (1), acute rejection (2) and chronic rejection (2). The remaining grafts (54.5%) all functioned for >1000 d (range: 1023-3746 d). The pre-transplant anti-A titer was determined in 6 pts; in 4 it was low (2) and in 2 it was high (8). Graft survival in all but one of these patients (whose titer was 8 and who suffered a non-rejection-related vascular thrombosis) was > or =2 yr. In summary, ABO-mismatched RT in pediatric patients is an uncommon practice. However, the adult experience and our preliminary pediatric experience suggests that evaluation of recipient isoagglutinin levels in this setting may be helpful in the selection of donor/recipient pairs in whom mismatched transplantation can be successful.