Functional natural killer T cells in experimental mouse strains, includingNK1.1(-) strains

Natural killer T (NKT) cells are a newly discovered subset of lymphocytes. It appears that this subset has potential as important regulators of immune responses. But because there are relatively few NKT cells in lymphoid orga ns and because of technical difficulties in detecting NKT cells in most mou se strains, the roles of NKT cells have not been fully identified and littl e attention has been paid to the roles of NKT cells in immunological experi ments in which NK1.1(-) strains were used. To examine the existence of func tional NKT cells in various strains of experimental mice, including NK1.1(- ) strains, we utilized a-galactosylceramide (KRN7000) which is thought to r eact specifically with NKT cells. Indeed, we could confirm that early cytok ine (IL-4 and IFN-gamma) secretion at 2 h after the injection of KRN7000 wa s dependent on NKT cells. With this in vivo system, we have successfully de tected the presence of functional NKT cells in various mouse strains, inclu ding AKR/N, BALB/c, C3H/HeJ, C3H/HeN, C57BL/6, C.B-17, CBA/N, NC, NOD, SJL, W/W-v, aly/aly and aly/+. Notable increases of serum IL-4 were detected in W/W-v and aly/+ strains, and defective response of IFN-gamma in SJL mice a nd that of IL-4 in NOD mice were observed This is the first report to show the functional significance of NKT cells in cytokine secretion in various m ouse strains in response to a ligand for the T cell receptor of NKT cells.