IgE-mediated activation of human heartin vitro

Abstract

We used human cardiac tissue from the right atrial appendages of patients undergoing corrective heart surgery to study content andde novo synthesis of mediators in the human heart. Human heart tissue contained 1.7±0.1 μg/g wet weight of histamine (mean±S.E.M.) and spontaneously produced 6-keto-PGF_1α (38.4 ng/g wet weight/min), PGF_2α (1.9 ng/g wet weight/min), PGE (1.7 ng/g wet weight/min) and thromboxane B₂ (T×B₂) (1.7 ng/g wet weight/min). Spontaneous release of PGD₂, leukotriene C₄ and histamine was negligible. Rabbit anti-human IgE (1–10 μg/ml) dose-dependently induced the release of histmaine (5 to 15% of the total histamine content) and of PGD₂ (5 to 100 ng/g of wet tissue). The effect of anti-IgE was dose-related and reached a maximum after 30–45 min of incubation. A significant linear correlation (r_s=0.90; p<0.001) was found betweende novo synthesis of PGD₂ and the secretion of histamine induced by anti-IgE challenge of human heart. These results support the concept that PGI₂ is the main, but not the sole, product of arachidonic acid metabolism synthesized by human heartin vitro. Additionally, anti-IgE challenge of human heartin vitro induces the release of histamine and PGD₂. The local concentrations of these mediators appear high enough to play some role in the modulation of several cardiac functionsin vivo.