Histamine release from human pulmonary mast cells.

Area of Science:

• Immunology
• Cell Biology
• Pulmonary Medicine

Background:

• Human lung mast cells are key players in allergic responses.
• Understanding their mediator release mechanisms is crucial for developing targeted therapies.
• Previous studies often relied on rat mast cells, necessitating direct human cell investigation.

Purpose of the Study:

• To characterize the mediator release properties of human pulmonary mast cells.
• To compare the degranulation responses of human mast cells with those of rat mast cells.

Main Methods:

• Human lung tissue was dispersed using collagenase to isolate cell suspensions.
• Mast cell presence was confirmed, and spontaneous histamine release was assessed.
• Cells were sensitized with anti-human IgE and challenged to measure histamine release.
• Responses to concanavalin A, dextran, calcium ionophores (A23187, ionomycin), and specific releasers (48/80, MCD-peptide) were evaluated.

Main Results:

• Isolated human lung cell suspensions contained approximately 8% mast cells with low spontaneous histamine release (7%).
• Passive sensitization with anti-human IgE induced significant histamine release upon challenge.
• Concanavalin A triggered release, but dextran did not; phosphatidyl serine had no potentiating effect.
• Calcium ionophores A23187 and ionomycin effectively elicited histamine release.
• Human pulmonary mast cells were refractory to basic releasers 48/80 and MCD-peptide.

Conclusions:

• Human pulmonary mast cells exhibit distinct mediator release patterns compared to rat peritoneal mast cells.
• Their responsiveness to IgE, concanavalin A, and calcium ionophores highlights key activation pathways.
• Refractoriness to certain basic releasers suggests unique signaling or effector mechanisms in human mast cells.