In vitro desensitization to lipopolysaccharide suppresses tumour necrosis factor, interleukin-1 and interleukin-6 gene expression in a similar fashion.
Like blood monocytes, the human monocytic cell line Mono Mac 6 can be stimulated by lipopolysaccharide (LPS) at 1 microgram/ml to produce high levels of cytokines. When Mono Mac 6 cells are stimulated for 4-6 hr at 1 x 10(6)/ml, supernatants contain tumour necrosis factor (TNF) at an average of 60 U/ml and interleukin-6 (IL-6) at an average of 1000 U/ml. IL-1 is not detected in the supernatant, but after three freeze-thaw cycles cell-associated IL-1 can be detected (100 U/ml) and with similar amounts of IL-alpha and -beta. Preculture of Mono Mac 6 cells with LPS at 10 ng/ml for 3 days results in cells refractory to subsequent stimulation by LPS at 1 microgram/ml. In the refractory desensitized cells, production of all three cytokines is down-regulated, with a more than 10-fold reduction in protein production. For all three cytokines, this desensitization appears to be regulated at the transcript level, with a strong reduction in specific mRNA as detected by Northern blot analysis. Furthermore, Mono Mac 6 cells can be stimulated by Staphylococcus aureus (LPS contamination less than 10 pg/ml) to produce cytokines. This type of stimulus is unable to overcome desensitization, in that the secretion of TNF in LPS-precultured Mono Mac 6 cells was 10- to 100-fold lower than in Mono Mac 6 cells without LPS preculture. These data show that desensitization in Mono Mac 6 cells affects all three cytokines tested and that it extends to other activating signals, such as staphylococci.
Ziegler-Heitbrock
H W
HW
Institute for Immunology, Munich, Germany.
Blumenstein
M
M
Käfferlein
E
E
Kieper
D
D
Petersmann
I
I
Endres
S
S
Flegel
W A
WA
Northoff
H
H
Riethmüller
G
G
Haas
J G
JG
D000942:Antigens, Bacterial / Q000276:immunology; D002460:Cell Line; D002478:Cells, Cultured; D003888:Desensitization, Immunologic; D015870:Gene Expression / Q000276:immunology*; D006801:Humans; D007375:Interleukin-1 / Q000235:genetics*; D015850:Interleukin-6 / Q000235:genetics*; D008070:Lipopolysaccharides / Q000276:immunology*; D009113:Muramidase / Q000235:genetics; D013211:Staphylococcus aureus / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics*
D000942:Antigens, Bacterial; D007375:Interleukin-1; D015850:Interleukin-6; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D009113:Muramidase