Antibodies and Antigens: Immune System Components

Antibodies and Antigens

Immunity is one of the most basic and essential survival skills we possess as humans. It protects us from pathogens, such as bacteria and viruses, which can cause diseases. Our immune system's response is triggered by two main components: antibodies and antigens.

What Are Antibodies?

Antibodies, also known as immunoglobulins, are large Y-shaped molecules produced by an immune system. They contain five identical polypeptide chains arranged in pairs and are held together by disulfide bonds between the N-termini of the light chains and the C-termini of the heavy chains. There are five classes of antibodies: IgA, IgD, IgE, IgG, and IgM.

Functions of Antibodies

Antibodies serve various functions in our bodies, including neutralizing viruses, promoting complement activation, helping in inflammation, facilitating opsonization, and agglutination. For instance, they can neutralize a virus by binding to a specific site on the virus and blocking its entry into human cells. Similarly, they can promote complement activation, which leads to the destruction of pathogens. Additionally, they help in inflammation by attracting white blood cells to the damaged area. Opsonization involves marking a foreign particle for phagocytosis, while agglutination refers to the clumping of bacteria or red blood cells.

Production of Antibodies

Antibody production occurs during an immune response. When a pathogen enters our body, our immune system detects it using specialized immune cells called T and B cells. T cells produce chemicals called lymphokines that activate B cells, causing them to divide and mature into plasma cells, which produce and secrete antibodies.

What Are Antigens?

Antigens are molecules on the surface of cells or microorganisms that trigger an immune response when they come into contact with our bodies. They can also be present in proteins, polysaccharides, lipids, or DNA fragments found in bacteria, viruses, fungi, parasites, or other organisms.

Role of Antigens

The primary role of antigens is to bind to specific antibodies produced by the immune system, which triggers an immune response called agglutination and the activation of complement. This immune response helps our body to recognize and destroy foreign pathogens, protecting us from diseases.

Classes of Antigens

There are two main classes of antigens: proteins (which contain amino acids) and polysaccharides (sugar chains). Protein antigens include bacteria like Streptococcus, fungi like Candida albicans, and viruses like HIV. Polysaccharide antigens can be found on bacterial cell walls, such as Escherichia coli or *Haemophilus influenzae_.

In conclusion, antibodies and antigens play a crucial role in our immune system's defense against pathogens. Antibodies are produced by our immune system in response to detecting antigens, which trigger an immune response that ultimately protects us from various infections and diseases. Understanding these components is essential for developing vaccines, immunotherapies, and treatments for infectious diseases.