Immu-14. single cell rnaseq of pbmcs from newly-diagnosed glioblastoma patients

Abstract INTRODUCTION A multitude of recently published papers have found immunosuppression caused by glioblastoma (GBM) is not limited to the tumor microenvironment and impacts the peripheral immune system. Our group has recently reported an expansion of granulocyte macrophage precursors, a subset of hematopoietic stem and progenitor populations (HSPCs), in glioma-bearing mice relative to healthy, age-matched controls. Thus we sought to determine if GBM causes cell fate dysfunction in CD34+ HSPCs in patients. METHODS CD34+ cells were magnetically isolated from peripheral blood of newly-diagnosed GBM patients and healthy age-matched donors and processed for single-cell RNA sequencing. CD34+ cells were magnetically isolated from peripheral blood of newly-diagnosed GBM patients and healthy age-matched donors and processed for single-cell RNA sequencing using the 10X Genomics platform. CellRanger was used for primary analysis with default parameters. After quality control removal of doublets, dead, and low quality cells automated cell type annotation was performed using the Azimuth Hubmap Consortium human bone marrow reference. The annotated single cell object was then read into R and Seurat was used for differential expression analysis and visualization. RESULTS AND CONCLUSIONS There we no significant expansions of stem and progenitor populations. GBM patient CD34+ samples had upregulation of VWF, a marker of myeloid-bias cell subset. Within the mature immune cell compartments, we observed a significant expansion of NK cells in GBM patients including 1,997 genes differentially expressed in the NK cell cluster between cohorts. This includes downregulation of SLAMF6, which triggers cytolytic activity in NK cells, in GBM patients. Upregulation of early NK cell activation markers CD69 and JUN were seen in GBM patient samples. These results strongly suggest NK are likely activated in the context of GBM, but may not be functional.