Phenotypic changes in lymphocyte subpopulations in pediatric renal-transplant patients after T-cell depletion

Background. T-cell depletion causes a novel homeostasis in lymphocyte subsets in adult transplant recipients. Little is known about long-term changes in pediatric patients. Methods. Twenty-one pediatric renal-transplant patients (mean age 11.8 years) were selected according to their initial postoperative immunosuppressive therapy: (1) baseline immunosuppression (111) with cyclosporine, azathioprine, and steroids, n=11; and (2) 111 plus polyclonal antibodies, n=10. Lymphocyte surface markers were measured in the mean 2.3 years after transplantation and analyzed between the patient groups and in regard to 46 age-matched healthy controls. Results. The patient groups did not differ with respect to age, sex, renal function, and previous infections. Total lymphocyte counts, CD4(+) T-cell numbers, and distribution of naive to memory CD4(+) T cells were not different between transplant groups and controls. However, patients with postoperative T-cell depletion showed significantly lower ratios of CD4(+) to CD8(+) T cells, elevated CD8(+) T-cell numbers, increased counts of CD8(+) T cells coexpressing CD57, and higher numbers of CD8(+) cells with a naive phenotype. In addition, the numbers of double-positive T cells and lymphocytes bearing both natural killer (NK) and T-cell markers were elevated in the patients with postoperative depletion. NK and B-cell counts were lower in the transplant patient groups compared with the healthy controls. Conclusions. Pediatric transplant patients show characteristic long-term changes in lymphocyte subsets after T-cell depletion. In contrast with adult patients, these perturbations are less pronounced and predominant in the CD8(+) T-cell compartment.