Mast cells have long been known for their role in allergic reactions, releasing chemicals that trigger symptoms such as tissue swelling and inflammation. However, researchers at the Max Planck Institute of Immunobiology and Epigenetics in Freiburg and the University of Münster have discovered a new talent of mast cells: the ability to capture and use neutrophil immune cells. This finding sheds new light on how the immune system functions during allergic reactions. Inflammation, the body’s response to harmful stimuli, involves various immune cells working together to protect the body. The type of immune cells involved can vary, influencing the outcome of the inflammatory response.
During allergic responses, mast cells play a critical role in initiating inflammation and are filled with granules containing pro-inflammatory substances. These granules are released when mast cells encounter allergens, leading to allergic reactions. A research group at the MPI of Immunobiology and Epigenetics used specialized microscopy to observe real-time interactions between mast cells and other cell types during allergic reactions in living mouse tissues. They discovered a surprising interaction, with neutrophils found inside mast cells, a phenomenon that was unexpected and highlights the power of intravital microscopy. Neutrophils are frontline defenders of the immune system, responding quickly to threats by engulfing invaders, releasing antimicrobial substances, and forming traps known as “neutrophil extracellular traps.”
The researchers found that mast cells release a substance called leukotriene B4 to attract neutrophils, leading to their trapping inside mast cells. This process, known as “mast cell intracellular trap” (MIT), allows mast cells to boost their own function and metabolism by recycling the materials from trapped neutrophils. Trapped neutrophils eventually die, and their remains are stored inside mast cells. This discovery has implications for chronic allergic conditions where inflammation occurs repeatedly, as mast cells can use neutrophils to enhance their capabilities, triggering additional immune responses and sustaining inflammation and immune defense.
The researchers confirmed the formation of MITs in human samples and are investigating the interaction between mast cells and neutrophils in mast cell-mediated inflammatory diseases in humans. This newfound understanding of how mast cells and neutrophils work together adds a new layer to our knowledge of allergic reactions and inflammation. The researchers are exploring whether this discovery could lead to new approaches in treating allergies and inflammatory diseases. By revealing how mast cells can utilize neutrophils to enhance their function and sustain inflammation, this research may offer insights into potential therapeutic targets for chronic allergic conditions and inflammatory diseases.
Overall, this study highlights the complex interactions between different immune cells during allergic responses and inflammation. The discovery of mast cells trapping neutrophils and utilizing their components to boost their own function sheds new light on how the immune system functions in response to allergens and harmful stimuli. Further research in this area could lead to new treatments for chronic allergic conditions and inflammatory diseases, offering new insights into the role of mast cells and neutrophils in immune responses.