What is the role of antibodies in body response to infection?

Antibodies play a critical role in the body's response to infection. They are specialised proteins produced by the immune system that serves as a defence mechanism against foreign substances such as bacteria, viruses, and toxins. Here's an overview of their role:

Recognition and Binding:

Antibodies are designed to recognise specific antigens, which are molecules on the surface of pathogens or foreign substances. Each antibody has a unique binding site that allows it to attach to a specific antigen. This recognition and binding process is highly specific, enabling the immune system to target and identify specific pathogens.

Neutralisation:

Once antibodies bind to antigens, they can neutralise the pathogens by preventing them from infecting cells. Antibodies can block critical sites on the pathogen's surface, such as attachment sites or enzymes, rendering them unable to cause infection. By neutralising pathogens, antibodies prevent their spread and reduce the risk of disease.

Opsonisation:

Antibodies can mark pathogens for destruction by other components of the immune system, a process known as opsonisation. They coat the surface of pathogens, making them more recognisable by phagocytic cells such as macrophages and neutrophils. These phagocytic cells then engulf and destroy the antibody-coated pathogens.

Complement Activation:

Antibodies can activate the complement system, a cascade of proteins that play a crucial role in immune defence. When antibodies bind to antigens, they trigger the activation of complement proteins, which leads to the formation of membrane attack complexes. These complexes create pores in the pathogen's cell membrane, causing cell lysis and destruction.

Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC):

Antibodies can also mediate the killing of infected cells through ADCC. In this process, antibodies bind to infected cells and recruit specialised immune cells called natural killer (NK) cells. NK cells recognise the antibody-coated infected cells and release cytotoxic granules that destroy them.

Memory Response:

When the body encounters a pathogen for the first time, the immune system produces antibodies to fight the infection. These antibodies are called primary antibodies. However, upon subsequent encounters with the same pathogen, the immune system can mount a faster and more robust response due to the production of memory antibodies. Memory antibodies are long-lived and provide long-term protection against specific pathogens.

Overall, antibodies are essential components of the body's immune response to infection. They recognise and neutralise pathogens, enhance their destruction by other immune cells, and provide long-term immunity through memory responses. Without antibodies, the body would be vulnerable to a wide range of infections and diseases.