Antibodies are Y-shaped proteins produced by the immune system that play a crucial role in defending the body against foreign invaders such as bacteria, viruses, and parasites. Their primary function is to recognize and neutralize these harmful substances, preventing them from causing illness.
Here's a breakdown of the key functions of antibodies:
- Neutralization: Antibodies bind to pathogens, blocking their ability to attach to and infect cells. For example, antibodies can neutralize viruses by preventing them from entering cells, or they can block bacterial toxins from binding to their target cells. [Reference: https://my.clevelandclinic.org/health/body/22971-antibodies, https://pubmed.ncbi.nlm.nih.gov/26104200/]
- Opsonization: Antibodies coat pathogens, making them more easily recognized and engulfed by phagocytic cells, like macrophages and neutrophils. This process enhances the efficiency of phagocytosis, a crucial mechanism of the immune system. [Reference: https://my.clevelandclinic.org/health/body/22971-antibodies, https://study.com/academy/lesson/what-are-antibodies-definition-function-types.html]
- Complement Activation: Antibodies can trigger the complement system, a cascade of proteins that leads to the lysis (bursting) of pathogens. This process is particularly important in the defense against bacteria. [Reference: https://pmc.ncbi.nlm.nih.gov/articles/PMC4159104/, https://pubmed.ncbi.nlm.nih.gov/34314289/]
- Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC): Antibodies can bind to infected cells or tumor cells, marking them for destruction by natural killer (NK) cells. NK cells are part of the innate immune system and can kill cells without prior sensitization. [Reference: https://www.mblbio.com/bio/g/support/method/antibody-role.html, https://pubmed.ncbi.nlm.nih.gov/34314289/]
Antibodies circulate throughout the blood and lymph, providing a constant defense against infections. They also play a role in immune memory, enabling the body to mount a faster and more effective response to subsequent encounters with the same pathogen.
