A NOVEL MONOCLONAL-ANTIBODY PERMITTING RECOGNITION OF NKT CELLS IN VARIOUS MOUSE STRAINS

By immunizing mouse lymphoma cell line tMK-2U derived from intermediat e TCR cells of BALB/c nude mouse, U5A2-13 monoclonal antibody (mAb, a rat IgG2a) was established. U5A2-13 antigen (Ag) was expressed on arou nd 65% of TCRint cells in the liver of the various mouse strains inclu ding both NK1.1(-) and NK1.1(+) mouse strains, while NK1.1 Ag was expr essed only in NK1.1(+) C57BL/6 mouse strain, Among CD3(+) cells, 26.3% cells co-expressed U5A2-13 Ag and NK1.1(+) Ag, while small proportion s of the CD3(+) cells were U5A2-13(+)NK1.1(-) (9.2%) or U5A2-13(-)NK1. 1(+) (4.4%). Among NK1.1+ cells, 54.9% cells co-expressed CD3 and U5A2 -13 Ag, while some proportions of the cells were U5A2-13(+)CD3(-) (19. 4%) or U5A2-13(-)CD3(+) (9.8%), It was found that approximately 85% of NK1.1(+)CD3(+) cells coexpressed U5A2-13 Ag, U5A2-13 Ag with low fluo rescence intensity was also expressed on 55% of NK1.1(+)CD3(-)NK cells , U5A2-13 Ag immunoprecipitated from tMK-2U cells consisted of three p roteins, which were 65 kDa, 33 kDa and 32 kDa under both reducing and non-reducing conditions and these were apparently different from NK 1. 1 Ag, These results indicated that U5A2-13 mAb was able to define a si milar population to NK1.1(+)CD3(+)T cells and to 55% of NK1.1(+)CD3(-) NK cells in various strains, through recognizing a different molecule from NK1.1 Ag. (C) 1998 Academic Press.