Genetic and functional characterisation of killer cell immunoglobulin like receptors (KIR) of rhesus macaques (Macaca mulatta)

Abstract

This PhD thesis reports the characterisation of the genetic diversity of killer cell immunoglobulin like receptors (KIR) as well as interactions between KIR and MHC class I molecules in the rhesus macaque (Macaca mulatta). In humans, it has been that KIR haplotypes have an influence on the resistance against various diseases. The rhesus macaque is a well established non-human primate model for several diseases such as AIDS. The diversity of KIR genes has been analysed in previous studies; yet, a genotyping tool for rhesus macaque KIR genes has not been described so far and detailed information of distinct KIR genotypes and haplotypes was previously unavailable. Furthermore, specific interactions between KIR and MHC class I molecules have not been characterised so far. One aim of this study was to establish a KIR genotyping assay for the rhesus macaque and to determine distinct KIR genotypes and haplotypes. Eight new KIR cDNA sequences were isolated from a NK cell cDNA library. All these sequences code for KIR3D molecules, confirming the high diversity of lineages II KIR genes in rhesus macaques. Using these sequences and those available in public database, a set of 31 primers for KIR genotyping was established. 25 KIR genotypes could be identified in four families containing a total number of 70 animals. With segregation analyses in four rhesus macaque families, 21 haplotypes could be determined. The haplotypes varied in gene number between 5 and 11 KIR genes. The results show a comparable level of diversity and complexity between human and rhesus macaque KIR haplotypes. The second aim of this study was to identify specific interactions between KIR and MHC class I molecules and to define the interaction sites between these molecules. KIR Fc fusion proteins were used with different Mamu-A and -B transfectants and strong specific interactions were identified for two KIR molecules each of them with two Mamu-A molecules. No significant interaction was found with Mamu-B molecules. Fine mapping of the interaction sites was carried out for interacting KIRs (KIR3DLW03 and KIR3DL05) and revealed different binding patterns for these two KIR molecules. While the binding specificity of KIR3DL05 molecule shows similarities to the binding specificity in humans and was mainly determined by the α1 domain of the Mamu-A molecule, especially by the Bw epitope, the binding specificity of KIR3DL05 was influenced by the α1 and α2 domain of the Mamu-A molecule. The interaction pattern differs also in the amino acids of the KIR molecules that are involved in the interaction with the Mamu-A molecules. The knowledge of the established KIR genotyping and the newly discovered interactions between KIR and Mamu-A molecules will improve the power of the rhesus macaque as animal model and will reduce the number of animals needed for disease studies.