Can the interleukin-6 response to endotoxin be predicted? Studies of the influence of a promoter polymorphism of the interleukin-6 gene, gender, the density of the endotoxin receptor CD14, and inflammatory cytokines.
OBJECTIVE
To evaluate whether the -174 G/C promoter polymorphism of the interleukin-6 gene, gender, the monocyte density of the endotoxin receptor CD14, or the inflammatory cytokines tumor necrosis factor-alpha or interleukin-1beta influence the interleukin-6 response of whole blood to endotoxin.


METHODS
Analysis of interleukin-6 release from endotoxin-stimulated human whole blood.


METHODS
Medical research laboratory.


METHODS
Healthy human blood donors.


METHODS
None.


RESULTS
The interleukin-6 -174 G/C and the tumor necrosis factor -308 G/A promoter polymorphisms were determined by real-time polymerase chain reaction assay by using specific fluorescence labeled hybridization probes. Monocyte CD14 expression was assessed by flow cytometry. After incubation of whole blood with endotoxin, plasma concentrations of interleukin-6, tumor necrosis factor-alpha, and interleukin-1beta were measured by means of chemiluminescence. The interleukin-6 concentrations were lower (p = .005) in individuals who were CG heterozygotes compared with individuals homozygous for the C or the G. The difference between C and G homozygotes was not significant (p = .67). The interleukin-6 response was enhanced in men compared with women (p = .015). There was no correlation between interleukin-6 concentrations and monocyte CD14 density. Interleukin-6 concentrations correlated with the concentrations of tumor necrosis factor-alpha (r = .59, p = .01) and interleukin-1beta (r = .47, p = .01). There was no linkage between the tumor necrosis factor -308 and the interleukin-6 -174 polymorphisms.


CONCLUSIONS
The interleukin-6 response to endotoxin was influenced by gender and correlated with the concentrations of more proximal cytokine tumor necrosis factor-alpha and interleukin-1beta. The interleukin-6 -174 G/C promoter polymorphism can only partly predict the interleukin-6 response of human whole blood to endotoxin stimulation, and the results were different from previous reporter gene assays that reported higher interleukin-6 concentrations for the G allele. Tumor necrosis factor -308 G homozygotes produce the lowest tumor necrosis factor concentrations. The number of tumor necrosis factor -308 G homozygotes was not higher among interleukin-6 -174 heterozygotes, and thus this cannot account for their significantly smaller interleukin-6 production.
Heesen
Michael
M
Department of Anesthesiology and Intensive Care Medicine, University Hospital of Aachen, Germany.
Bloemeke
Brunhilde
B
Heussen
Nicole
N
Kunz
Dagmar
D
D000328:Adult; D004731:Endotoxins / Q000276:immunology*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood* / Q000235:genetics*; D018950:Lipopolysaccharide Receptors / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000276:immunology; D012737:Sex Factors; D018709:Statistics, Nonparametric; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D004731:Endotoxins; D007375:Interleukin-1; D015850:Interleukin-6; D018950:Lipopolysaccharide Receptors; D014409:Tumor Necrosis Factor-alpha