CONTRAST-MEDIA ARE INCOMPLETE SECRETAGOGUES ACTING ON HUMAN BASOPHILSAND MAST-CELLS ISOLATED FROM HEART AND LUNG, BUT NOT SKIN TISSUE

To investigate the mechanisms of anaphylactoid reactions to radiocontr ast media, in vitro mediator release induced by three iodinated contra st agents was examined using peripheral blood basophils and mast cells purified from human lung parenchyma, heart, and skin tissues. Three i odinated contrast agents, sodium and meglumine salts of ioxaglic acid, sodium and meglumine salts of ioxithalamic acid, and ioversol, were i ncubated with basophils purified from peripheral blood and human mast cells isolated and purified from different anatomical sites. Release o f preformed (histamine and tryptase) and de novo synthesized mediators (prostaglandin D-2 and leukotriene C-4) into the supernatans was dete rmined at various contrast medium concentrations after incubation for 60 min. Ioxaglate (0.2-0.3 M), ioxithalamate (0.3-0.5 M), and to a les ser extent ioversol (0.3-0.5 M) induced histamine release from basophi ls in a concentration-dependent manner. All three induced the release of preformed mediators (histamine and tryptase) from human lung, but n ot from skin mast cells. They also induced histamine acid tryptase rel ease from human heart mast cells. However, they did not induce the de novo synthesis of leukotriene C-4 or prostaglandin D-2 from human baso phils or any type of mast cell examined. Cross-linking of IgE by anti- IgE induced the release of leukotriene C-4 or prostaglandin D-2 from h uman basophils or mast cells. Mannitol, an osmotic stimulus, induced t he release of histamine from human basophils, but to a lesser extent f rom mast cells. These results show that: different contrast media can differ in their ability to release mediators from enriched preparation s of human basophils and mast cells. The three contrast agents examine d act on basophils and mast cells as incomplete secretagogues, causing the release of preformed mediators, but not the de novo synthesis of chemical mediators. It may be useful to measure plasma tryptase levels to detect adverse reactions caused by iodinated radiographic contrast materials.