Mast Cells in Inflammation and Disease: Recent Progress and Ongoing Concerns

Area of Science:

• Immunology
• Cell Biology
• Evolutionary Biology

Background:

• Mast cells are ancient immune cells, existing before adaptive immunity and antibody development.
• In marine invertebrates like *Styela plicata*, analogous cells called 'test cells' share morphological and mediator characteristics with vertebrate mast cells.
• Mast cells are primarily known for their role in acute allergic reactions, such as anaphylaxis, mediated by immunoglobulin E (IgE).

Purpose of the Study:

• To review the evolutionary origins of tissue mast cells.
• To explore the dual functions (beneficial and detrimental) of mast cells in innate and adaptive immunity.
• To discuss mast cell heterogeneity and plasticity in the context of health and disease.

Main Methods:

• Literature review of mast cell origins and functions.
• Analysis of morphological and mediator characteristics of mast cells and test cells.
• Discussion of mast cell heterogeneity and plasticity.

Main Results:

• Mast cells likely evolved to perform crucial functions preceding antibody-mediated immunity.
• Evidence suggests mast cells possess both beneficial and detrimental roles.
• Mast cell heterogeneity and plasticity contribute to their diverse functions in various conditions.

Conclusions:

• Mast cells represent an evolutionarily conserved lineage with fundamental roles in immunity.
• Understanding mast cell plasticity is key to deciphering their involvement in both health and disease.
• Further research is needed to resolve open questions regarding mast cell biology.