[Relationship between cytotoxicity of two types of TNF-alpha and intracellular free calcium concentration in target cells].
OBJECTIVE
To compare the changes of free calcium concentration in target cells killed by transmembrane tumor necrosis factor-alpha(TM-TNF-alpha) and secretory TNF-alpha(S-TNF-alpha).


METHODS
The cytotoxicity of two types of TNF-alpha was tested by bioassay. The intracellular Ca(2+) concentration was determined by Frua-2.


RESULTS
TM-TNF-alpha had cytotoxic effect on all 6 kinds of target cells, whereas S-TNF-alpha could kill only two of them. The cytotoxic activity of both types of TNF-alpha was accompanied by a dramatically increase of intracellular free Ca(2+) concentration. The intracellular Ca(2+) concentration in the target cells treated with S-TNF-alpha was obviously reduced by pretreating target cells with 10 micromol/L calcium chelator EGTA for 30 minutes (P<0.01) and the cytotoxicity of S-TNF-alpha was significantly inhibited (P<0.01), while the pretreatment with EGTA had no effect on the intracellular Ca(2+) concentration in the target cells treated with TM-TNF-alpha and the cytotoxicity of TM-TNF-alpha.


CONCLUSIONS
These results suggest that both types of TNF-alpha increase Ca(2+) concentration in target cells by promoting the redistribution of intracellular free calcium and only S-TNF-alpha seems to be able to accelerate the influx of extracellular calcium into the target cells.
Shi
Wen-fang
WF
Department of Immunology, Tongji Medical College, Huazhong University of Sciences and Technology, Wuhan 430030, China.
Yin
Bing-jiao
BJ
Xiong
Ping
P
Gong
Fei-li
FL
Li
Zhuo-ya
ZY
D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000473:pathology; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D004533:Egtazic Acid / Q000494:pharmacology; D005260:Female; D018922:HL-60 Cells; D018197:Hepatoblastoma / Q000473:pathology; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology; D016393:Lymphoma, B-Cell / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000145:classification / Q000494:pharmacology*
D014409:Tumor Necrosis Factor-alpha; D004533:Egtazic Acid; D002118:Calcium