ANTIGENS (Immunogens)

ANTIGENS (Immunogens)

• Immunogenicity the capacity production of specific protective humoral or cellular immunity.
• Specific reactivity the capacity to be recognized by the antibodies and T cell producd.
• Foreignness the recognition of a body as nonself (foreign proteins are excellent antigen).
• Size must be at least approximately 10 kilo Daltons to be recognized.
• Shape tertiary and quaternary structure determines the extent of antigenicity.
• Epitope part of Ag that react with BCR and TCR.
-is the restriction portion of antigen molecule that determines the specificity of the reaction with an antibody.
-is the antibody-binding site on an antigen for a specific antibody.
-generally contains four to six amino acid or sugar residues.
• Hapten are Ag but not immunogens
-is a small foreign  molecules that is not immunogenic by itself but can bind to an antibody molecule already formed to it.
-can be immunogenic if coupled to a sufficiently large carrier molecule.
Example- DNP, PAM, IAA.