IgE-mediated hypersensitivity in human heart !tissue: Histamine release and functional c,hanges
In experiments described herein, it was observed that IgE-mediated hypersensitivity can result in significant histamine and thromboxane release from human myocardium, suggesting that the human heart may participate as a target organ in allergic reactions. Muscle units (pectinate muscles) were isolated from human atrial appendages, removed routinely during corrective cardiac surgery, and were allowed to beat spontaneously in a tissue bath. Remnants of each atrial specimen were chopped and added to the tissue bath. Challenge of the atrial tissue with goat antiserum to human myeloma IgE caused histamine and thromboxane B2 release and marked increases in contractility and spontaneous rate. In contrast, challenge with nonspecific goat antiserum or with antiserum from which anti-IgE antibodies had been removed caused neither mediator release nor changes in rate or contractility. The histamine H2-receptor antagonist cimetidine inhibited the inotropic and chronotropic changes but not the histamine release.