[Effects on activity of mouse NK cells by inhibitory Ly49 receptors blockade]

To observe the effects on antitumor activity of mouse NK cells and the mixed lymphocyte reaction with blocking the interaction between the inhibitory Ly49 receptor on mouse NK cell and MHC-I molecules on target cells with monoclonal antibody.

NK cells were isolated from splenocytes of C57BL/6J mouse with immunomagnetic method. YAC-1 and M1 cells were used as target cells, the cytotoxicity of NK cells was examined with mixed lymphocyte reaction before and after treatment of anti-Ly49 monoclonal antibody.

The cytotoxicity of NK cells to M1 cell was significantly augmented (10.7% +/- 0.5% compared with 84.4 % +/- 2.9%), and the clone-forming capacity of M1 cell was inhibited remarkably (8.2 % +/- 2.2% compared with 94.0% +/- 3.3%) with the increase of concentration of the antibody (0 approximate, equals 60 microg/ml) (P <0.05). The difference of cytotoxicity to YAC-1 cells was only found between 0 microg/ml and 60 microg/ml groups (P <0.05). In mixed lymphocyte reaction, after pretreated with antibody, the proliferation of splenocytes of BALB/C mouse was inhibited (0.398 +/-0.025 compared with 0.128 +/- 0.014), and statistical difference was observed only between antibody groups of 0 microg/ml and 60 microg/ml (P<0.05).

Blocking the inhibitory Ly49 receptor on NK cells with monoclonal antibody augments the cytotoxicity to target cells.