[The expression of interleukin-6 mRNA and autosecretion in human leukemic cells].
OBJECTIVE
To make a comprehensive and systematic study on the constructive expression of IL-6 mRNA and IL-6 autosecretion in human leukemic cells and discuss the effect of IL-6 autosecretion on the specific binding of IL-6-PE40 fusion protein to targeted leukemic cells.


METHODS
Semi-quantitative RT-PCR, sequencing and ELISA were used to detect the constructive expression of IL-6 mRNA and autosecretion level of IL-6 protein in human leukemic cell lines, such as U937, HL60, KG1, TF1, K562, HuT28, CEM and Raji.


RESULTS
The relative expression level of IL-6 mRNA in myelocytic, monocytic and erythrocytic leukemic cell lines including HL60, U937, KG1 and TF1 and lymphoblastic leukemic cell lines such as CEM, HuT28 and Raji is very weak, ranging from 0.03 to 0.07. However, K562, an chronic myelocytic leukemic cell line, had the highest level 1.25 among the 8 leukemic cell lines and the level was also higher than that of the positive control U266 multiple myeloma cell line. Based on ELISA assay of IL-6, there were remarkable differences between the 8 leukemic cell lines, their secretion of IL-6 could be divided into 3 levels, i.e. high, moderate and low secretion type.


CONCLUSIONS
These observations imply that the intrinsic expression and secretion of IL-6 differ obviously among different leukemic cell lines. Autocrine IL-6 may prevent IL-6-PE40 fusion protein from specific binding to targeted leukemic cells and consequently affect its specific killing toxicity.
Liu
S
S
Department of Immunology, The Affiliated Hospital of the Academy of Military Medical Science, Beijing 100039, China.
Xi
Y
Y
Guo
S
S
Liu
N
N
Tu
M
M
Kong
F
F
D045744:Cell Line, Tumor; D015973:Gene Expression Regulation, Leukemic; D018922:HL-60 Cells; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics; D020014:K562 Cells; D007938:Leukemia / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D020298:U937 Cells
D015850:Interleukin-6; D012333:RNA, Messenger