T cells, expressing natural killer cell markers (NKT cells), play roles in eradicating tumors as well as being involved in the onset of autoimmunity, such as insulin-dependent diabetes and graft rejection secreting. Most T cells require CD28 co stimulatory signalling during antigenic responses for complete activation. However, NKT cells do not respond well to CD28 co stimulation. Thus, alternate molecules are responsible for co stimulating NKT cells to be defined. One strong candidate for primary co stimulatory molecule of CD8+ NKT cells is 4-1BB (CDw137) because 4-1BB is selectively induced in CD8+ NKT cells during early antigenic stimulation with IL-12. Previously, 4-1BB has been demonstrated to be involved in anti-tumor and anti-viral activity by CD8+ T cells. Therefore, Dr. Kim's major effort is to study the potential of 4-1BB in promoting CD8+ NKT cells for the anti-tumor cytotoxic responses. Recently, dendritic cells have drawn attention as a potent antigen presenting cells for cytolytic T cell-mediated anti-tumor responses. Since surface of dendritic cells are highly enriched with ligand for 4-1BB, Dr. Kim hopes to seek the possibility that 4-1BB may be a key molecule for priming of CD8+ NKT cells by dendritic cells during anti-tumor responses. CD8+ NKT cells are rarely detected in human umbilical cord blood and gradually increase after birth. He also investigates the possible involvement of 4-1BB in production of CD8+ NKT cells by using human umbilical cord blood. His long-term goal is to implement the research outcome for developing anti-leukemia therapeutic tools through cord blood transplantation.
Immunology
