Grant: Discovery Launch Supplement

gd T cells are a subset of human T lymphocytes with diverse functions. Similar to ab T cells, they express a T cell antigen receptor (TCR) resulting from somatic recombination. Notably, most gd T cells can recognize and eliminate transformed cells independently of Human Leukocyte Antigen (HLA) restriction, distinguishing them from ab T cells. Additionally, gd T cells express receptors associated with Natural Killer (NK) cells, giving them two distinct recognition pathways to detect stressed cells. Key players in this NK-like function are the diverse Killer cell Immunoglobulin-like Receptors (KIRs), which interact with HLA class I and play a crucial role in NK cell immunity, by monitoring HLA class I on target cells, and facilitating maturation and education to recognize stressed cells lacking HLA class I. Up to 60% of circulating gd T cells may express KIRs. Yet, unlike NK cells, the role of these receptors in gd T cell immunity remains largely uncharted. Thus, for a thorough understanding of gd T cell immunity, it is imperative to explore the involvement of KIRs in gd T cell repertoire development, maturation and education. This program will: Part 1. Define how KIRs and cytomegalovirus (CMV) shape the gd T cell repertoire. We will analyze adult human circulating gd T cells, employing advanced techniques like spectral flow cytometry and high-throughput sequencing of gd TCR repertoires. We will assess the impact of CMV by involving both CMV+ and CMV- individuals in our assays. This will reveal how KIRs and CMV influence gd T cell diversity, enhancing our understanding of their role in gd T cell immunity. Part 2. Define the contribution of KIRs to the gd T cell education. We will conduct functional studies using spectral flow cytometry and primary gd T cells to investigate how gd T cells expressing KIRs respond to CMV+targets with reduced HLA class I expression. Additionally, we will employ HLA class I-deficient cells transfected with single HLA class I allotypes to assess gd T cell functional responses to specific interactions between KIRs and their respective HLA class I ligands. These investigations will reveal the intricate interplay between KIRs and HLA class I molecules in gd T cell immunity. Part 3. Characterize metabolic profiles and epigenetic modifications in gd T cell subsets. To investigate the connection between KIR expression, cell metabolism, development, and function, we will utilize the innovative Single Cell Metabolism by Profiling Translation Inhibition (SCENITH) method for single-cell metabolic profiling of gd T cell subsets. Additionally, we will apply Assay for Transposase-Accessible Chromatin with Sequencing (ATAC-Seq) to assess chromatin accessibility in various gd T cell subsets, encompassing both resting and CMV-exposed cells. Through this research, we seek to enhance our understanding of gd T cell immunity and shed light on the biological significance of KIRs in gd T cell development and function.