The impact of donor source, recipient age, pre-operative immunotherapy and induction therapy on early and late acute rejections in children: a report of the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS).

Acute rejection is a frequent event in pediatric transplantation. In addition to graft loss, acute rejection episodes stimulate the development of chronic rejection and inhibit growth in children post-transplantation. In this study, we analyzed our data from 1987 through 1996 to identify acute rejection episodes in children. In 2,520 living donor (LD) transplants there were 2,540 rejection episodes (rejection ratio: 1.1), and in 2,579 cadaver donor (CD) transplants 3,653 episodes were observed (rejection ratio: 1.32). For LD recipients the first rejection occurred sooner when there was at least one HLA-DR mismatch (RR=1.6, p<0.001) and prophylactic T-cell antibody was not used (RR=1.4, p<0.001). For CD transplants absence of prophylactic T-cell antibody (RR=1.2, p<0.001) and donor age below five years were risk factors (RR=1.5, p<0.001). Late initial acute rejections were seen in 327 of 1,471 patients (22.2%) who were rejection free at one year. At risk for the development of late rejections were children over the age of six years at transplantation (RR=1.7, p<0.001) and children of non-white origin (RR=1.5, p <0.002). For LD transplant recipients in the age range of 0-5 years, irreversible rejection was observed in 8.7% compared to 4.1% for older children (RR=1.46, p<0.001). Similar results for CD transplants were 12.6% versus 6.6% (RR=1.5, p<0.00). The high frequency of rejection episodes in children and the greater irreversibility in younger children suggest pediatric patients may have a more robust immune response. Current ongoing studies in the molecular mechanisms of the pathogenesis of rejection in surveillance biopsies of children may help determine if this hypothesis is valid.