Contribution of membrane-associated cytotoxic proteins to cytolysis of L929 and K562 target cells mediated by LAK cells with different phenotypes.

We have demonstrated that the relative contribution of secreted and membrane-associated proteins to the cytotoxicity of LAK cells depended on LAK cell phenotype: the cytotoxicity of CD16+ CD8+ CD3- LAK cells was associated mainly with membrane-bound proteins, and the activity of CD3+ CD8+ CD16- LAK cells was due mainly to secreted soluble proteins. The cytotoxic activity of membrane fractions of LAK cells against cell line L929 was determined by 40-, 32- and 21-kDa proteins for LAK cells bearing NK-specific markers and due to proteins of 34 and 21 kDa in the case of 'CTL-like' LAK-cells.