Resistance of multidrug‐resistant lines to natural killer‐like cell‐mediated cytotoxicity

Multidrug resistance (MDR) refers to a complex phenotype that describes a number of features characterized primarily by resistance to a wide range of structurally unrelated drugs. In this paper we investigated the relationship between drug resistance and resistance to NK‐mediated cytotoxicity. Studies with two independently selected multidrug‐resistant cell lines indicated that increased drug resistance was associated with both an increased resistance to NK‐mediated cytotoxicity and increased levels of membrane P‐glycoprotein expression. This resistance to cytotoxicity appears to result partly from an alteration in the membrane structure of the target cells inasmuch as there was a reduction in effector:target cell recognition. Resistance to NK‐mediated cytotoxicity should be included with the numerous pleiotropic changes associated with the multidrug resistance phenotype.—W oods , G.; L und , L. A.; N aik , M.; L ing , V.; O chi , A. Resistance of multidrug‐resistant lines to natural killer‐like cell mediated cytotoxicity. FASEB J. 2: 2791‐2796; 1988.