RESUMO
The monocytic cell line U937 is a frequently used model in studies on the cytotoxic effect of tumour necrosis factor (TNF). Two sublines of this cell line, termed U937(G) and U937(M), revealing different patterns of response to this cytokine, have been identified. The U937(G) cells, similarly to the cells obtained from ATCC, were resistant to the cytotoxic action of TNF in the absence of the protein-synthesis blocker cycloheximide (CHX). The U937(M) cells, however, were sensitive to the cytotoxic action of TNF both in the presence and absence of cycloheximide. Genetic analysis of the U937 sublines confirmed their common origin. The described U937 sublines may be useful models for analysis of the mechanisms of response to TNF. Additionally, our observation underscores the variability of the U937 cell line, which is described by most authors as a TNF-sensitive line.
