title: Resistance to streptolysin O in mammalian cells treated with oxygenated derivatives of cholesterol. Cholesterol content of resistant cells and recovery of streptolysin O sensitivity.
abstract: Cultures of L cells and HeLa cells were made resistant to the cytolytic toxin, streptolysin O, by incubating them in the presence of 20 alpha-hydroxycholesterol or 25-hydroxycholesterol. Such cells were also found to be more resistant to the cytotoxic effects of saponin and digitonin, agents known to interact with membrane cholesterol. Sterol synthesis in L cells that had been treated with either of the oxygenated derivatives of cholesterol was reduced by almost 90%, and the free cholesterol content of streptolysin O-resistant HeLa and L cells fell to approx. 50% of control cell levels. Significant recovery of sensitivity to streptolysin O occurred in about 6 h when refractory L cells were incubated in serum or cholesterol. Partial recovery was observed when the cultures were incubated for 24 h in mevalonate or lipid-depleted serum. The results provide further support for the role of membrane cholesterol in the cytotoxic action of streptolysin O on mammalian cells.
mesh_terms: D001426:Bacterial Proteins; D001790:Blood Physiological Phenomena; D002784:Cholesterol / Q000378:metabolism*; D004351:Drug Resistance; D006367:HeLa Cells / Q000187:drug effects; D006801:Humans; D006888:Hydroxycholesterols / Q000494:pharmacology*; D007739:L Cells / Q000187:drug effects; D008798:Mevalonic Acid / Q000494:pharmacology; D013301:Streptolysins / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D006888:Hydroxycholesterols; D013301:Streptolysins; C025964:streptolysin O; C025813:20-hydroxycholesterol; C007997:25-hydroxycholesterol; D002784:Cholesterol; D008798:Mevalonic Acid