What are the characteristics of antigens?

Immunogenicity: Antigens are capable of inducing an immune response in the body. The immune system recognizes antigens as foreign and mounts an immune response against them.

Specificity: Different antigens have different structures, which allow the immune system to distinguish between them and produce specific antibodies against each one.

Reactivity: Antigens specifically react with antibodies that are produced against them. This reaction forms the basis of many immunological assays.

Foreignness: Antigens are foreign to the body, meaning that they are not normally found in the body. The immune system is programmed to recognize and respond to foreign antigens.

Size, Shape, and Complexity: Antigens can vary greatly in size, shape, and complexity, ranging from small molecules to large complex structures such as proteins and polysaccharides.

Antigenic determinants or Epitopes: The portion of an antigen that binds to an antibody is called an antigenic determinant or an epitope. It is the specific region that the antibody recognizes and binds to.