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Tumour necrosis factor-like activity on paraformaldehyde-fixed monocyte monolayers
1Institute of Cancer Research, University of Trondheim, Norway.
Abstract:
A tumour necrosis factor (TNF)-related protein appears to be associated in part with the monocyte surface membrane, since paraformaldehyde-fixed monocyte monolayers induced cytolysis of WEHI 164 clone 13 cells. Cytolysis was inhibited by neutralizing antisera raised against recombinant TNF (rTNF) and against the monocyte-derived cytotoxic factor, CF, which presumably is identical to natural TNF. Moreover, crude monocyte membrane preparations also contained cytotoxic activity, which was inhibited by antisera raised against rTNF and CF, and this activity was associated with particulate structures as it did not pass through filters with a pore size of 0.2 micron. Gamma-interferon (gamma-IFN)-activated monocytes fixed with paraformaldehyde had more TNF-like activity than fixed unactivated monocytes, and the crude membrane preparations from gamma-IFN-activated monocytes contained about five times more TNF-like activity than preparations from unactivated monocytes.
Insights
Tumor necrosis factor (TNF)-related proteins are found on monocyte membranes, causing cell death. Gamma-interferon activation increases this TNF-like activity on monocytes.
Area of Science:
- Immunology
- Cell Biology
Background:
- Tumor necrosis factor (TNF) is a key inflammatory cytokine.
- Monocytes play a crucial role in the immune response.
Purpose of the Study:
- To investigate the presence and activity of TNF-related proteins on the monocyte surface.
- To determine the effect of gamma-interferon (gamma-IFN) activation on monocyte-associated TNF-like activity.
Main Methods:
- Paraformaldehyde-fixed monocyte monolayers were used to assess cytotoxic activity against WEHI 164 clone 13 cells.
- Neutralizing antisera against recombinant TNF (rTNF) and cytotoxic factor (CF) were employed for inhibition studies.
- Crude monocyte membrane preparations were analyzed for cytotoxic activity and characterized by filtration.
- Comparison of TNF-like activity between activated and unactivated monocytes.
Main Results:
- Fixed monocytes induced cytolysis of WEHI 164 clone 13 cells, indicating TNF-related activity.
- Cytolysis was inhibited by antisera against rTNF and CF, confirming the involvement of TNF.
- Cytotoxic activity was associated with particulate structures in monocyte membrane preparations.
- Gamma-IFN-activated monocytes exhibited significantly higher TNF-like activity compared to unactivated monocytes.
Conclusions:
- A TNF-related protein is associated with the monocyte surface membrane.
- Monocyte-derived cytotoxic factor (CF) is likely identical to natural TNF.
- Gamma-IFN activation enhances the TNF-like cytotoxic activity of monocytes.