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Effect of bacterial purified antigenic fractions on natural defence mechanisms
W Luini1, S Sozzani, L Braceschi
1Laboratory of Immunology and Oncology, Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.
Abstract:
The in vitro ability of bacterial purified antigenic fractions to interfere with the immune system has been investigated on human mononuclear cells from peripheral blood. Exposure of purified monocytes to the drug at concentrations from 1 to 1000 micrograms/ml, for different periods from 0 to 18 h, significantly increased cell-mediated cytotoxicity against TU5 target cells. Moreover, monocytes exposed for 1 to 18 h to drug concentrations from 0.1 to 1000 micrograms/ml released significant amounts of tumor necrosis factor alpha in a dose-dependent manner in the culture supernatants. The drug was also tested on natural killer (NK) cell activity; mononuclear cells exposed to antigenic fractions for different periods showed a significant increase of NK cytotoxic activity against K562 target cells after 3 and 6, but not 0 and 18 h. Active concentrations were from 1 to 100 micrograms/ml, higher and lower doses being ineffective. Bacterial purified antigenic fractions thus have some ability to interfere in vitro with mechanisms of cytolysis mediated by cells and soluble factors.
Insights
Bacterial antigenic fractions enhance immune cell cytotoxicity and tumor necrosis factor alpha release in vitro. This suggests these bacterial components can modulate immune responses, impacting cell-mediated and soluble factor-driven cytolysis.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Bacterial antigenic fractions are components of bacteria that can interact with the host immune system.
- Understanding how these fractions influence immune cells is crucial for developing immunomodulatory therapies.
- Previous research has explored bacterial components' effects on immune cells, but specific mechanisms require further elucidation.
Purpose of the Study:
- To investigate the in vitro effects of bacterial purified antigenic fractions on human mononuclear cells.
- To assess the impact of these fractions on cell-mediated cytotoxicity and cytokine release.
- To determine the influence on natural killer (NK) cell activity.
Main Methods:
- Human peripheral blood mononuclear cells, including monocytes and NK cells, were exposed to bacterial antigenic fractions in vitro.
- Cell-mediated cytotoxicity was measured against TU5 target cells.
- Tumor necrosis factor alpha (TNF-α) release was quantified in culture supernatants.
- NK cell activity was assessed against K562 target cells.
Main Results:
- Monocytes exposed to antigenic fractions showed significantly increased cell-mediated cytotoxicity against TU5 cells.
- Monocytes released significant amounts of TNF-α in a dose-dependent manner.
- A significant increase in NK cell cytotoxic activity against K562 cells was observed at 3 and 6 hours post-exposure, with effective concentrations between 1-100 µg/ml.
Conclusions:
- Bacterial purified antigenic fractions demonstrate an in vitro ability to modulate immune cell functions.
- These fractions can enhance monocyte-mediated cytotoxicity and TNF-α production.
- The study indicates that bacterial antigenic fractions can interfere with cytolysis mechanisms involving both cellular and soluble factors.