Localization, phenotype and function of CD8⁺ T cells in the bone marrow

Chapter 1 introduces the complex relationship between T cells and hematopoietic stem cells. T cells act as a double-edged sword upon allogeneic hematopoietic stem and progenitor cell (HSPC) transplantation, as they are the cause of graft-versus-host disease, but provide anti-tumor activity and support engraftment of HSPCs. Chapter 2 offers insight into the composition of bone marrow (BM) found in the numerous bones throughout the body. Differences in the bone structure (ratio of cortical and trabecular bone) have been shown to influence the function of the BM. Chapter 3 investigates if BM effector memory CD8⁺ T cells, which express CD69, are genuine tissue-resident memory T cells. Chapter 4 continues on the main topic of BM T cells and addresses if T cells, next to their immune function, also have a hematopoietic supporting role in the BM. This question is based on the fact that memory CD8⁺ T cells, especially those with a memory phenotype contribute to HSPC engraftment. Chapter 5 explores the enhancement of protective immune responses by increased co-stimulatory signals. Lastly, in Chapter 6, we continue with the discussion of our findings. We focus on what others and we have uncovered about the Localization, Phenotype and Function of CD8⁺ T cells in the BM, and speculate on how these cells can contribute to the HSPC transplantation field.