[Recognition and lysis by natural killers of tumor cells with participation of laminin].

According to the data obtained in the present work, the receptor complex of mouse natural killers (NK) includes laminin, antibody to which blocks EK-activity (NKA regardless of the presence of complement. Preincubation of mouse splenocytes with anti-laminin serum led to a decrease in their NKA towards tumor cells-targets (CT), the NKA activity decreasing 2 times with respect to cultivated cells of rat hepatoma HTC, while 10 times - to cultivated cells of human erythroblastosis K562. Pretreatment of aplenocytes with noraml nonimmune serum did not lead to a change of NKA. Quite different was the pattern after the tumor cell preincubation with anti-laminin serum: pretreatment of CT K562 led to a twofold decrease in sensitivity of these cells to NK-lysis, whereas the pretreatment of CT K562, on the contrary, made them twice sensitive to NK-lysis. Electrophoretic separation of protein of CT plasma membranes with subsequent immunoblotting with anti-laminin immune serum revealed the presence oflaminin on HTC cell plasma membrane, which was identified as laminin 8/9 by the mass-spectrometry method, while no laminin was detected on K562 cells. Preincubation of splenocytes with laminin did nor affect NKA with respect to CT K562 and HTC. Pretreatment of CT K562 and HTC with laminin decreased the NKA to zero. The obtained data allow suggesting a doubtless participation of laminin and its receptors in CT cytolysis by NK.