What are the functions of antibodies?

Key functions of antibodies include: 

• Neutralization: Antibodies can bind to pathogens such as viruses or toxins, preventing them from accessing host cells and infecting or damaging them.
• Opsonization: By acting as opsonins and binding to the pathogen, antibodies mark pathogens for destruction by phagocytic cells such as macrophages and neutrophils. 
• Complement activation: Antibodies can activate the complement pathway by binding to microbial surfaces, which releases substances that make up the membrane attack complex (MAC) that functions by punching holes in the plasma membrane of the pathogen, resulting in cell lysis and death. 
• Regulation of immune responses: Antibodies can modulate immune responses by interacting with other immune cells and molecules, helping to regulate inflammation and prevent excessive immune activation.
• Formation of Immune Complexes: Multiple antigens and antibodies bind together to form immune complexes, which restricts the diffusing ability of antigens and facilitates phagocytosis by making it easier for phagocytes to identify and ingest pathogens.