IgE-mediated hypersensitivity in human heart tissue: histamine release and functional changes.

Area of Science:

• Cardiology
• Immunology
• Allergy Research

Background:

• Allergic reactions involve immunoglobulin E (IgE)-mediated hypersensitivity.
• The heart's role in allergic reactions as a target organ is not fully understood.

Purpose of the Study:

• To investigate the human heart's potential role as a target organ in IgE-mediated hypersensitivity reactions.
• To examine the release of mediators and functional changes in human atrial tissue upon IgE challenge.

Main Methods:

• Isolation of human atrial muscle units (pectinate muscles) from surgical specimens.
• Incubation of isolated atrial tissue in a tissue bath.
• Challenge of atrial tissue with specific goat anti-human IgE antiserum and control antisera.
• Measurement of mediator release (histamine, thromboxane B2) and assessment of contractility and spontaneous rate.

Main Results:

• Specific IgE challenge induced significant histamine and thromboxane B2 release from human atrial tissue.
• IgE challenge resulted in marked increases in myocardial contractility and spontaneous rate.
• Control antisera did not elicit mediator release or functional changes.
• Cimetidine partially inhibited the inotropic and chronotropic effects but not histamine release.

Conclusions:

• Human myocardium can release histamine and thromboxane in response to IgE-mediated hypersensitivity.
• The human heart may function as a target organ in allergic reactions.
• Histamine receptors appear to mediate some of the observed cardiac functional changes.