Macrophages are a type of white blood cell that play a vital role in immune defense. They are part of the innate immune system, which is typically the first line of defense against foreign antigens. 

Macrophages serve several functions that support immune function. 

• Destroy foreign organisms that enter the body by phagocytosis, which involves engulfing and digesting the microorganisms
• Act as scavengers, clearing out debris and dead cells by phagocytosis, allowing for repair following damage by injury or infection 
• Facilitate antigen presentation, which activates lymphocytes and consequently the immune response mechanism
• Assist in tissue repair by clearing inflammatory signals and releasing anti-inflammatory cytokines such as interleukin 10