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 370C, and challenged in the presence of 1 IAM 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 106 cells to 0.049, 0.056, and 0.129 nmol per 106 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.Adenobine mediates numerous biological processes including coronary vasodilation (1), steroidogenesis (2), and lipolysis (3). Adenosine release, originally demonstrated during myocardial hypoxia (4) and later during neuronal firing (5), has been documented in lung tissue exposed to an hypoxic environment (6) or antigen challenge (7). Normal resting plasma adenosine levels average 0.3 ,uM (8), and tissue levels may increase up to 10-fold under provocative conditions (6). Rat peritoneal and mouse bone marrow mast cells stimulated by specific antigen or the calcium ionophore, A23187, release significantly more granule-associated, preformed mediators when challenged in the presence of micromolar concentrations of adenosine (9, 10). This appears to be at least in part due to binding of adenosine to cell-surface receptors which, when occupied by an agonist, initiate an increase in whole-cell cyclic AMP concentrations. The concentration of intracellular adenosine, which is freely transported across the plasma membrane (11), is dependent on the rate of release of adenosine from AMP by nucleotidases and on the rate of removal of adenosine by adenosine kinase or adenosine deaminase (12). To achieve high local levels of adenosine that would influence the mast cell secretory process, neighboring cells or the mast cells themselves would have to produce and release adenosine. To investigate whether mast cell activation results in augmented extracellular ...

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“…Adenosine can be released by many cell types, including mast cells, and also can be generated extracellularly from ATP (2,3). Several lines of evidence suggest that adenosine may contribute to the pathophysiology of a variety of diseases, including myocardial infarction, cancer, asthma, and chronic obstructive pulmonary disease (4 -7).…”

Changes in Adenosine Metabolism in Asthma. A Study on Adenosine, 5&#39-NT, Adenosine Deaminase and Its Isoenzyme Levels in Serum, Lymphocytes and Erythrocytes

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Synergistic effects of calcium‐mobilizing agents and adenosine on histamine release from rat peritoneal mast cells

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