2014 Volume 3 Issue 1 Pages 12-26
Natural killer (NK) cells are an important member of the innate immune system. “Missing self” is one of the mechanisms for NK cell response by detection of the loss of self-major histocompatibility complex (MHC) class I expression. This refined mechanism of NK cells, which are believed to have emerged much later than B and T cells based on the evolutional convergence of their variable receptors, rarely trigger autoimmune disorders. After hematopoietic stem cell transplantation (HSCT), donor’s NK cells can recognize the HLA differences between recipient and donor by using killer immunoglobulin-like receptors (KIRs). KIR-mismatched HSCTs have been tried in hope of inducing graft-vs-leukemia effects, with mixed results. The difference in outcomes may be attributable to a number of factors; different diagnoses, HLA-matching, donor source, GVHD prophylaxis, diverse range of KIRs and different NK cell conditions such as inhibiting, activating, licensing and disarming. On the other hand, the dominance of KIR group A haplotype and HLA-C group 1 type in the Japanese population will make it simpler to explore the best recipient-donor combination. This review summarizes our emerging understanding of KIR-HLA diversity, especially in HSCT, to select the optimal donor based on HLA and KIR.
