Transfection of L929 cells with complement subcomponent C1q B-chain antisense cDNA inhibits tumor necrosis factor-alpha binding to mediate cytotoxicity and nitric oxide generation
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H Jiang1, C A Stewart, S Y Tan
1Oklahoma Medical Research Foundation, Oklahoma City 73104-5046, USA.
Abstract:
The role of complement subcomponent C1q in the modulation of TNF-alpha binding to L929 cells to mediate cytotoxicity and nitric oxide (NO) generation was investigated. Transfection of L929 with murine C1q B-chain antisense plasmid cDNA rendered them markedly less susceptible to TNF-mediated cytotoxicity coincident with a decreased capacity for TNF-alpha binding and expression of cell surface C1q protein. The inhibitory effects of L929 transfection with C1q B-chain antisense were transiently expressed at 24 hr post-transfection with full recovery of cellular functions by 72 hr. Transfected L929 cells were fully reconstituted in their TNF-alpha binding and in their cytotoxic response following exposure to soluble C1q which was bound to their cell surface. Transfection with C1q B-chain antisense also significantly inhibited NO generation by L929 cells in response to stimulation by TNF-alpha, IFN-alpha/beta, and LPS. Taken together, these results indicate that endogenously synthesized C1q is prerequisite for binding of TNF-alpha to L929 cells to mediate cytotoxicity and NO generation.
Insights
Complement C1q protein is essential for tumor necrosis factor-alpha (TNF-α) to bind L929 cells, mediating cell death and nitric oxide (NO) production. Inhibiting C1q synthesis blocks these TNF-α effects.
Area of Science:
- Immunology
- Cell Biology
Background:
- Tumor necrosis factor-alpha (TNF-α) is a key cytokine in inflammation and immunity.
- The role of complement subcomponent C1q in TNF-α signaling is not fully understood.
Purpose of the Study:
- To investigate the role of C1q in TNF-α-mediated cytotoxicity and nitric oxide (NO) generation in L929 cells.
Main Methods:
- L929 cells were transfected with C1q B-chain antisense plasmid.
- TNF-α binding, cytotoxicity, and NO generation were assessed.
- Effects of soluble C1q were evaluated.
Main Results:
- C1q B-chain antisense transfection reduced TNF-α binding and cytotoxicity.
- Nitric oxide generation was inhibited by C1q B-chain antisense transfection.
- Soluble C1q restored TNF-α binding and cytotoxic response.
Conclusions:
- Endogenously synthesized C1q is required for TNF-α binding to L929 cells.
- C1q is a prerequisite for TNF-α-mediated cytotoxicity and NO generation.