Tumour necrosis factor-like activity on paraformaldehyde-fixed monocyte monolayers

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.