Characterization of four new monoclonal antibodies that recognize mouse natural killer activation receptors

With the aim of identifying natural killer (NK) activation receptors, we im munized BALB/c mice with (BALB/cxB6)F1 NK LAK cells and made B-cell hybrido mas, These were screened for monoclonal antibody (MAb) reacting with an NK activation receptor by using an antibody-induced redirected lysis (AIRL) as say against FcR-bearing P815 targets, Four hybridomas, clones 1C10, 1F10, 2 D10 and 4G4, were selected for further characterization. Protein G-purified MAbs from these clones activated both resting and IL-2 activated B6 or F1 NK cells in the AIRL assay, 1F10 MAb, but not the other three MAbs, could c ompete for the binding of anti-NK1.1 (PK136) MAb to Fl NK cells. The four M Abs were screened for their ability to bind to or activate NK cells from th e mouse strains SJL/J, DBA/2, 129/J, C3H/J, and BALB.K. None showed activit y except 1C10, which could bind to and activate SJL/J NK cells. When member s of the NKR-P1 family from both B6 mice (A, B, and C genes expressed) and SJL mice (only A and B genes expressed) were expressed in Jurkat cells and tested for their antibody reactivity, PK136 MAb was found to recognize B6 N KR-P1C and SJL/J NKR-P1B; 1C10 MAb was found to recognize NKR-P1-A, -B and -C from B6, but not NKR-P1A or B from SJL/J; and 1F10 MAb was found to reac t only with B6 NKR-P1C.