The human cardiac mast cell: localization, isolation, phenotype, and functional characterization

Area of Science:

• Immunology
• Cardiology
• Cell Biology

Background:

• Mast cells (MCs) are immune cells involved in allergic reactions and inflammation.
• The presence and function of mast cells in human cardiac tissue have not been well-characterized.
• Understanding cardiac mast cells (CMCs) is crucial for investigating cardiac inflammatory and fibrotic processes.

Purpose of the Study:

• To isolate and characterize human cardiac mast cells (CMCs).
• To compare the properties of CMCs with mast cells from other tissues (uterus, skin, lung).
• To investigate the functional responses of CMCs, including histamine release.

Main Methods:

• Human heart tissue from cardiomyopathy patients undergoing transplantation was used.
• Cardiac mast cells (CMCs) were isolated via enzymatic digestion.
• Characterization involved toluidine blue staining, immunofluorescence, monoclonal antibodies (MoAbs), and histamine measurement.

Main Results:

• Substantial amounts of CMCs were found in atrial appendages (0.5–1.5% of isolated cells), but not in ventricular tissue.
• CMCs expressed surface IgE, c-kit receptor (CD117), CD45, and CD54, and were identified as MCTC type (tryptase and chymase positive).
• Stimulation of IgE or SCF receptors on CMCs induced histamine secretion, similar to lung and uterus MCs.

Conclusions:

• Human cardiac mast cells (CMCs) are a novel mast cell type predominantly located in the atrial appendages.
• CMCs exhibit surface antigen and functional characteristics similar to mast cells found in the lung and uterus.
• These findings suggest a potential role for CMCs in cardiac inflammatory responses and disease.