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Adenosine release from stimulated mast cells
Abstract:
Adenosine release has been documented in lung tissue exposed to hypoxic conditions or antigen challenge. Exogenous adenosine potentiates mediator release from stimulated rat serosal and mouse bone marrow-derived mast cells. To investigate the production and release of adenosine from stimulated mast cells, rat serosal mast cells were purified on metrizamide gradients, sensitized with anti-dinitrophenol IgE for 30 min at 37 degrees C, and challenged in the presence of 1 microM deoxycoformycin with either dinitrophenol-conjugated bovine serum albumin antigen, the calcium ionophore A23187, or compound 48/80. Reactions were terminated by centrifugation, and the supernatants and pellets were assayed for adenosine and ATP content, respectively, by high performance liquid chromatography. The adenosine concentration of the supernatants increased from 0.036 +/- 0.003 nmol per 10(6) cells to 0.049, 0.056, and 0.129 nmol per 10(6) cells 60 sec after challenge with antigen, 48/80, or A23187, respectively. After ionophore stimulation, increased extracellular adenosine was evident by 15 sec, peaked by 60 sec, and remained constant for at least 5 min. A significant decline in stimulated ATP levels was observed within 30 sec, suggesting that the enhanced adenosine concentrations may result from the breakdown of ATP. Cultured mouse bone marrow-derived mast cells under similar conditions also displayed augmented extracellular adenosine levels with A23187 challenge. This endogenous source of adenosine may act locally through a positive feedback mechanism to potentiate immediate hypersensitivity reactions.
Insights
Mast cells release adenosine when stimulated, potentially amplifying allergic reactions. This study shows adenosine production from stimulated mast cells, suggesting a positive feedback loop in hypersensitivity.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Adenosine release is observed in lung tissue under hypoxia or antigen exposure.
- Exogenous adenosine enhances mediator release from stimulated mast cells.
Purpose of the Study:
- To investigate adenosine production and release from stimulated mast cells.
- To explore the role of endogenous adenosine in mast cell-mediated hypersensitivity reactions.
Main Methods:
- Purified rat serosal mast cells were sensitized and challenged with antigen, calcium ionophore A23187, or compound 48/80.
- Adenosine and ATP levels in supernatants and pellets were quantified using high-performance liquid chromatography.
- Similar experiments were conducted with cultured mouse bone marrow-derived mast cells.
Main Results:
- Stimulated mast cells showed increased extracellular adenosine concentrations.
- Adenosine levels peaked by 60 seconds post-stimulation, particularly after ionophore challenge.
- A decline in ATP levels suggested adenosine originates from ATP breakdown.
- Both rat and mouse mast cells exhibited augmented extracellular adenosine.
Conclusions:
- Mast cells produce and release adenosine upon stimulation.
- Endogenous adenosine may potentiate immediate hypersensitivity reactions via a positive feedback mechanism.