Antigenicity and specificity T cell epitopes B cell epitopes Receptor TCR BCR MHC necessary non-necessary Character linear short natural polypeptide peptide polysaccharides Size 8~12aCD8)5~15aa 1217aa(CD4*t) 57monosaccharides ype linear determinant conformational determinant: linear determinant Location everywhere of ag surface of Ag
Antigenicity and specificity T cell epitopes B cell epitopes Receptor TCR BCR MHC necessary non-necessary Character linear short natural polypeptide peptide polysaccharides Size 8～12 aa(CD8+T) 5 ～15 aa 12～17aa(CD4+T) 5 ～7monosaccharides Type linear determinant conformational determinant ; linear determinant Location everywhere of Ag surface of Ag
Antigenicity and specificity 4. Hapten-carrier effect Carrier Hapten Antibodies to hapten Immunize rabbit Antibodies to carrier Hapten-carrier conjugate Antibodies to conjugate of hapten and carrier Injection with: Antibodies formed Hapten (NP) one Protein carrier (BSA) anti-BSA Hapten-carrier Anti-DNP (major) conjugate (DNP-BSA) Anti-BSA(minor) Anti-DNP/BSA (minor)
Antigenicity and specificity 4. Hapten-carrier effect
Antigenicity and specificity *common antigen and cross-reaction Cross reactions Anti-A Anti-A Anti-A Ab Ab Ab Ag A Ag b AgC Shared epitope Similar epitope
Antigenicity and specificity *common antigen and cross-reaction
Factors influencing immunogenicity A Contribution of the Immunogen 1. Foreignness The immune system normally discriminates between self and non-self such that only foreign molecules are immunogenIC
Factors influencing immunogenicity A. Contribution of the Immunogen 1. Foreignness - The immune system normally discriminates between self and non-self such that only foreign molecules are immunogenic
Factors influencing immunogenicity A Contribution of the Immunogen 2. Chemical Composition -In general, the more complex the substance is chemically the more immunogenic it will be Carbohydrates( polysaccharides ) haptens Lipids rarely immunogenic Nucleic acids poor immunogens Proteins: virtually all proteins are immunogenic
Factors influencing immunogenicity A. Contribution of the Immunogen 2.Chemical Composition - In general, the more complex the substance is chemically the more immunogenic it will be. Carbohydrates（polysaccharides）：haptens Lipids：rarely immunogenic Nucleic acids：poor immunogens Proteins：virtually all proteins are immunogenic