ＮＫＴ細胞の分化と機能

Abstract

Mouse NK1.1+αβ TCR+ (NKT) cells constitute a unique subset in T-cell population of the thymus and other lymphoid tissues. NKT cells express not only NK-lineage markers but also surface phenotypes of memory/activated T-cells. NKT cells produce a large amount of IL-4 immediately after cross-linking the T cell receptors (TCRs) with anti-CD3 antibody. On the other hand, these cells produce a large amount of IFN-γ upon stimulation through NKR-P1 with anti-NK1.1 antibody. Thus, with their differential productions of cytokines NKT cells may regulate terminal differentiation of T helper cells either to Th1 or to Th2. NKT cells also possess natural cytotoxicity against both autologous and allogeneic immature thymocytes through FasL-Fas interactions.It has been shown that the NKT cells express invariant Vα14 with a limited Vβ usage and are positively selected by CD1 or TL molecules expressed on CD4+8+ thymocytes. Thus, the developmental pathway of NKT cells is quite different from that of main-stream T-cells. However, using aly mutant mice we found that radio-resistant thymic component played an important role in generation of NKT cells as obseved in the development of main-stream T-cells.We also found that a normal population of NKT cells could be generated in the absence of canonical TCRα chain (Vα14Jα281).