Apoptotic and necrotic cytolytic processes induced by membrane associated proteins of LAK cells.

Cytolytic processes induced by membrane-associated proteins of human lymphokine-activated killer (LAK) cells with different phenotypes (CD3+, CD16-, CD8+ and CD16+, CD8+, CD3-) were studied using L929 and K562 types of target cells. Independently of the phenotype of effector cells and the type of target cells, total fractions of membrane proteins induced several different cytolytic processes occurring with different rates and involving different mechanisms of genome fragmentation. The membrane fraction induced, irrespective of the phenotype of LAK cells, mostly apoptotic processes in the L929 line. At the same time, cytolytic processes induced in K562 line differed by the mechanisms of DNA fragmentation. An inhibitor of lysosome activation, NH4Cl, and a Ca(2+)-binding reagent, ethylene glycol bis-(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA), induced partial inhibition of short-term cytolytic processes (developing within 1-5 h) but did not affect the development of long-term cytolytic processes requiring more than 6-8 h for their development.