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2-Chloroadenosine: a selective lethal effect to mouse macrophages and its mechanism
Abstract:
In our studies on the effects of purine compounds on immune responses in vitro, we found that 2-chloroadenosine (2-Cl Ado) exhibited a potent lethal effect on a viability of mouse adherent cells derived from the peritoneal cavity. The lethal effect was specific for adherent peritoneal cells (PC) (macrophages) and was prevented by exogenous addition of adenosine (Ado) or coformycin, a potent inhibitor of adenosine deaminase. A rapid decrease of intracellular ATP content (26% of control) in adherent PC was observed soon after 1 hr exposure to 2-Cl Ado (0.1 mM), and this decrease of ATP was comparable with that of monoiodoacetate (MIA, 0.1 mM)- or NaN3 (5 mM)-treated adherent PC. The ATP decrease by 2-Cl Ado was restored to 88 or 90% of control value by 1 hr addition of Ado or coformycin, respectively. Polymorphonuclear cells and lymphocytes to which 2-Cl Ado did not exhibit the lethal effect did not cause a significant ATP decrease of the cells. Therefore, the data suggested that the reason for the lethal effect on adherent PC treated with 2-Cl Ado could be attributed to a rapid decrease of ATP content at an early time. We assume that 2-Cl Ado competes with intracellular Ado in macrophages and then causes the adenosine starvation resulting in the ATP decrease.
Insights
2-chloroadenosine (2-Cl Ado) rapidly depletes ATP in mouse macrophages, causing cell death. This lethal effect on peritoneal cells (PC) is preventable with adenosine (Ado) or coformycin, suggesting adenosine starvation as the cause.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Purine compounds modulate immune responses.
- Peritoneal cells (PC) include macrophages, crucial immune cells.
- Adenosine (Ado) plays a role in cellular energy and immune function.
Purpose of the Study:
- To investigate the in vitro effects of 2-chloroadenosine (2-Cl Ado) on mouse peritoneal cells.
- To determine the mechanism behind the observed lethal effect of 2-Cl Ado on adherent PC.
- To explore the role of adenosine metabolism in 2-Cl Ado-induced cytotoxicity.
Main Methods:
- Exposure of mouse adherent peritoneal cells (macrophages) to 2-Cl Ado.
- Measurement of intracellular adenosine triphosphate (ATP) levels.
- Assessment of cell viability following treatment with 2-Cl Ado, adenosine (Ado), and coformycin.
- Comparison with cells treated with monoiodoacetate (MIA) and NaN3.
Main Results:
- 2-Cl Ado exhibited a potent lethal effect specifically on adherent PC (macrophages).
- A rapid decrease in intracellular ATP content was observed in PC treated with 2-Cl Ado.
- The lethal effect and ATP depletion were prevented by exogenous Ado or coformycin (adenosine deaminase inhibitor).
- Polymorphonuclear cells and lymphocytes were not affected by 2-Cl Ado.
Conclusions:
- The lethal effect of 2-Cl Ado on adherent PC is attributed to a rapid decrease in intracellular ATP levels.
- 2-Cl Ado likely competes with intracellular adenosine, leading to adenosine starvation and subsequent ATP depletion in macrophages.
- These findings highlight a specific mechanism of purine analog toxicity in immune cells.