Here's why:

* Lymphocytes: These are a type of white blood cell that are key players in the adaptive immune system. They include T cells, B cells, and natural killer cells. Mast cells are not lymphocytes and are part of the innate immune system.

* Phagocytes: These are cells that engulf and destroy pathogens and cellular debris. Examples include macrophages, neutrophils, and dendritic cells. While mast cells can release substances that attract phagocytes, they don't actively engulf and destroy pathogens themselves.

Mast cells are a type of granulocyte (a white blood cell with granules). They are important for the inflammatory response, releasing histamine and other chemicals that contribute to allergic reactions and inflammation.