Macrophages

Definition

Macrophages are white blood cells which form an important part of the innate immunity (non-specific). They are widely distributed in the body’s tissues. Macrophages have irregular shape with granules in their cytoplasm. They are phagocytes and play a crucial role in the initiation of the adaptive (specific) immune response. They engulf, remove, and digest necrotic cell debris, bacteria, and other foreign bodies and also play important roles in the early phases of infection and inflammation (Levinson 2006; Waugh and Grant 2001).

Known as antigen-presenting cells, macrophages migrate between tissues, and when they encounter pathogen/antigen, they engulf it, more importantly, they digest the antigen via specific intracellular processes and transport the most antigenic fragment to their own cell membrane and display it on their surface, where they carry it until they come into contact with the adaptive immune cells (T lymphocytes) in the lymphoid tissues. These lymphocytes...