Effect of soluble interleukin-6 receptor alpha and interleukin-6 secreted by polymorphonuclear leukocytes on tumor necrosis factor-alpha expression and its production by peripheral blood mononuclear cells.
BACKGROUND
It has recently been shown that soluble interleukin-6 receptor (sIL-6R) alone or complexed with interleukin (IL)-6, besides their regulatory role in a wide variety of both normal and abnormal biologic reactions mediated by IL-6, could be an effective stimulator of the cell function.


OBJECTIVE
The key question of the present study is whether the sIL-6Ralpha or sIL-6R with IL-6 released by polymorphonuclear leukocytes (PMN) can influence cytokine secretion such as tumor necrosis factor-alpha (TNF-alpha) by peripheral blood mononuclear cells (PBMC), which together with PMN develop the inflammatory and immune response of a host.


METHODS
Cells were isolated from heparinized whole blood of healthy persons. The PMN were cultured for 1 h at 37 degrees C in 5% CO(2). After incubation, the culture supernatant of PMN was removed and was added to PBMC. The PBMC were cultured for 1 h at 37 degrees C in the same conditions. In the culture supernatants and lysates of PMN, we examined the concentrations of sIL-6R by enzyme-linked immunosorbent assay (ELISA). TNF-alpha was measured at both protein and mRNA levels. Protein levels were determined by ELISA. To examine TNF-alpha mRNA expression, we isolated mRNA from PBMC after culture, using TRIZOL Reagent. The quantity of mRNA TNF-alpha was determined by the Quantikine mRNA assay.


CONCLUSIONS
The results obtained revealed that sIL-6R with IL-6 secreted by PMN may play a regulatory role in the immune response by modulating the TNF-alpha expression and its production by PBMC. This may have a significant influence on an early phase of the inflammation and other reactions mediated by TNF-alpha.
Jablonska
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Department of Immunology, Medical Academy of Bialystok, Washington 15A, 15-274 Bialystok, Poland. ewaj@amb.edu.pl
D002478:Cells, Cultured; D015870:Gene Expression / Q000276:immunology; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D009504:Neutrophils / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D018123:Receptors, Interleukin / Q000378:metabolism*; D019947:Receptors, Interleukin-6; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D012995:Solubility; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism
D015850:Interleukin-6; D012333:RNA, Messenger; D018123:Receptors, Interleukin; D019947:Receptors, Interleukin-6; D011993:Recombinant Fusion Proteins; D014409:Tumor Necrosis Factor-alpha; C104543:interleukin 6-interleukin 6 receptor fusion protein, recombinant