1. 1 Antigens 9 1. 1. 1 Proteins 9 1. 1. 2 Polysaccharides 10 I. 1. 3 Haptens and carriers 11 1. 2 Antibodies 12 1. 2. 1 Isotypes 12 1. 2. 2 Paratopes 16 1. 2. 3 Allotypes 16 1. 2. 4 Idlotypes 17 1. 2. 5 Immunoglobulin synthesis 17 1. 2. 6 Immunoglobulin purification 18 - Salt precipitation 20 - Gel filtration 20 - Ion exchange chromatography 20 - Immuno affinity fractionation 23 1. 3 Antibody production 24 Immunogenicity and antigenicity 24 1. 3. 1 Adjuvants 25 1. 3. 2 26 1. 3. 3 Immunization 1. 3. 4 Polyclonal antibodies 28 1. 3. 5 Monoclonal antibodies 29 1. 4 Antigen-antibody reaction 32 1. 4. 1 Specificity and affinity 32 1. 4. 2 Antigen-antibody reaction in liqUid phase 33 1. 4. 3 Antigen-antibody reaction in gel 34 1. 4. 4 Use of an immobilized phase 34 1. 5 Immunoassays 36 1. 5. 1 Assays based on precipitating antigen-antibody systems 36 I. 5. 1. 1 In liquid 37 37 - the ring test 3 ImmW100ssays in Food and Agriculture - the quantitative antigen-antibody precipitation in liquid 38 - agglutination and hemagglutination - nephelometIy and turbidimetIy 40 - Farr assay 42 1. 5. 1. 2 Immunoassays based on precipitating 43 antigen-antibody systems in gel 1. 5. 1. 2.