Natural killer (NK) cells are a major lineage of human lymphocytes with vital functions in innate immunity,adaptive immunity and hematopoietic cell transplantation. These functions are mediated by the diverseinteractions of highly polymorphic HLA-A, -B, and -C molecules with equally polymorphic killer immunoglobulin-likereceptors (KIR). They are complemented by the conserved interactions of HLA-E with CD94:NKG2heterodimers. The genes encoding KIR receptors and HLA ligands segregate independently, therebygenerating unique and diverse genotypes within families and populations. Phenotypically, this producesfunctionally distinct NK-cell repertoires, a natural variation that has profound effects on susceptibility toinfection and autoimmunity, on reproductive success, and the outcome of HCT. In SA1 we will extendretrospective statistical analyses of KIR and HLA variation in HCT to the highest levels of allele-level resolutionand precision. We have developed a novel target capture and next-generation sequencing methodology withcompatible bioinformatics tools. These will be used to determine complete KIR haplotype sequences anddefine allelic and allotypic variation throughout the KIR locus. In SA2 we will perform high-resolution analysis ofimmune reconstitution following HCT. Three cohorts will be studied -- HLA-matched, HLA-mismatched, andHLA-haploidentical transplants ? by comparing the mature NK cells of the donor to the reconstituting NK cellsin the transplant recipient. Longitudinal differences in immune phenotype will be assessed and compared.Functional capacity of the NK cells will be tested by challenge with target cells expressing self, altered-self,non-self and missing-self HLA class I. Early, intermediate and late stages in immune system reconstitution willbe evaluated. We will assess the reconstituted NK-cell response to exogenous stimuli (the CD16 directed-BiKEs and IL-15/IL-15R?-Fc superagonist complexes also studied in Projects 2 and 3) at the different stages.All analyses will consider KIR and HLA genotypes and CMV status. NK cells mature to acquire functionalimmunity through a process called education. SA3 of this project will analyze mature, educated NK cells anddetermine their functional capacity to recognize and respond to target cells expressing self, non-self, altered-self,and missing-self HLA class I. To achieve this goal, we will develop a high-throughput assay to assess NK-cellresponses to an extensive cell panel, in which each member cell expresses a different HLA class Iallotype. From these data, predictive rules for education, based on the KIR and HLA genotype and CMV statusof individuals, will be defined. Mass cytometry will be used to analyze NK cells and other lymphocytesubpopulations for individuals with selected combinations of KIR, HLA and CMV status. The results from thisproject will exponentially increase knowledge of the genetic factors influencing the outcome of HCT. Our long-termgoal is to obtain complete immunogenetic and biological understanding of the parameters affecting NKcell education. This knowledge should inform a wide range of studies aimed at improving human health.
Natural killer (NK) cells perform vital functions in human immunity and reproduction; which are controlled andmodulated by interacting families of genetically highly variable proteins specified by distinct and separatedregions of the human genome. This project will examine the impact of this variability on the functional potentialof NK cells and on the reconstitution of NK cell populations following hematopoietic cell transplantation astreatment for leukemia. This project will also advance knowledge of the genetic variation in NK cell function inhuman populations.
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