Reconstitution of NK Cell Receptor Repertoire after Pediatric Stem Cell Transplantation.

Interaction between killer immunoglobulin-like receptors (KIRs) and HLA class I ligands influence development of natural killer cell repertoire and response to allogeneic tissue. Recently several reports suggests donor/recipient KIR-ligand imcompatibility have great influence for outcome of allogeneic Hematopoietic Stem Cell transplantation (SCT). We examined recovery of the NK cell receptor after pediatric SCT to elucidate emergence of NKR repertoire and frequency after SCT is depend on whether donor or recipient type and effect of HLA disparity. [Patients and method] Nine patients receiving allogeneic SCT were examined. Expressions and frequency of KIR on NK cells were determined by flowcytometry using anti CD158a/h, 158b/j, 158e, 158i, 159a, 94, 56,and 3 antibodies. Donor and recipient KIR repertoire frequency prior to SCT were also examined. In cord blood transplantation, donor KIR repertoire was checked using residual thawed and infused cord blood. [Result] Among 9 patients, PBSCT were performed in 3 patients, CBT in 3, unrelated BMT in 3. HLA matched SCT was all 3 cases of unrelated BMT. KIR expression frequency was various in each patient. But in early phase, relatively both high percentage and absolute number of each KIR positive repertoire were observed, and then gradually decreased toward to 1 year after SCT. NK cell receptor repertoire reconstitution was generally well and rapid except for one patient who was treated with steroid pulse therapy for severe GVHD. KIR repertoire expression pattern at 1 year after SCT was similar to donor type compare to that of pre-SCT recipient. Donor/recipient HLA mismatch did not have obvious effect for NKR repertoire reconstitution. [Conclusion] NKR repertoire reconstitution after pediatric SCT depends on donor cell type.