Cytolytic processes induced by TNF in L929 and K562 differ in DNA fragmentation mechanisms.

Objective: Cytolytic activity of TNF was analysed at L929 and K562 tumor cell lines.

Methods: TNF-mediated cytotoxicity was studied within 10(-6)-10(-17) M concentration range after 18 h of incubation with target cells.

Results: TNF caused reliable cytotoxicity values in both cell lines, while L929 cells were more sensitive to cytolytic action of the protein than K562 cells. Three cytotoxicity maxima were detected at each cell line: at concentrations of 10(-6) M, 10(-17) M and 10(-15) M in K562 cells and at concentrations of 10(-7) M, 10(-11) M, 10(-14), 10(-16) M in L929 cells.

Conclusions: DNA fragmentation analysis demonstrated that all cytolytic processes induced by TNF in L929 cells are associated with apoptotic mechanism of cell death, while cytolytic process induced in K562 cells differed in DNA fragmentation patterns: cytolytic processes induced by 10(-6) M of TNF was of apoptotic type, while the other processes were not associated with internucleosomal DNA cleavage.