1. Antigen Receptors of Lymphocytes

2. Recognition: molecular patterns Recognition : molecular details (antigenic determinants) Innate immunity Aquired immunity (T i B lymphocytes) Genes: functional, germline encoded Genes: functional after DNA recombination Receptors for recognition Distribution: non-clonal distribution (same receptor on all cells within a cell line and even on the different lineages) Presence: multiple copies of the same receptor Distribution: clonal (cells within one clone exhibites receptor of the same specificity) Presence: multiple copies of different receptors

3. Antigen Receptors of Lymphocytes - Similiarity On the lymphocyte membrane Membrane Ig Antigen presenting cell Antibody (Immunoglobulin) T-cell receptor(TCR)

4. Antigen Receptors of Lymphocytes - Similiarity On the lymphocyte membrane Members of the immunoglobulin superfamily (domain structure) Ig domains

5. Antigen Receptors of Lymphocytes - Similiarity On the lymphocyte membrane Members of the immunoglobulin superfamily (domain structure) Two different chains

6. Antigen Receptors of Lymphocytes - Similiarity On the lymphocyte membrane Members of the immunoglobulin superfamily (domain structure) Two different chains Variable domains in contact with antigen (encoded by recombined DNA)

7. Antigen Receptors of Lymphocytes - Similiarity On the lymphocyte membrane Members of the immunoglobulin superfamily (domain structure) Two different chains Variable domains in contact with antigen (encoded by recombined DNA) Associated signal transduction molecules Activation motif Disulphide bond

8. Signal trasduction T cell receptor (TCR) Antigen presenting cell Signal trasduction Membrane Ig Antibody (Immunoglobulin) Antigen Receptors of Lymphocytes - Differences Recognizes: Free and membrane antigens Protein, polysaccharide, lipid, DNA, RNA Conformational and linear epitopes Recognizes : Antigens on the other cell membrane Peptides only (αβ TCR) Linear epitopes

9. Antigen Receptors of Lymphocytes - Differences Recognizes: Free and membrane antigens Protein, polysaccharide, lipid, DNA, RNA Conformational and linear epitopes Consists of: 4 polypeptide chains (2H and 2L) Recognizes: Antigens on the other cell membrane Peptides only (αβ TCR) Linear epitopes Consists of: 2 polypeptide chains (αβ or γδ)

10. Antibody structure Membrane of the B-cell

11. "for their discoveries concerning the chemical structure of antibodies" Gerald M. EdelmanRodney R. Porter Nobel prize for physiology and medicine 1972

12. Antibody structure Heavy chain Light chain Heavy chain Disulphide bonds Antigen binding sites

13. Antibody structure – papain digestion Hinge region Papain Fab fragments Fc fragment Interaction with other participants in the immune Response (cells, complement) Antigen binding Antibody structure

14. Antibody structure – pepsin digestion Pepsin F(ab) 2 fragment Antigen binding

15. MHC groove Anchoring amino acids Contact amino acid Peptide Polymorphic parts of MHC molecule T-cell receptor

16. TCR Co-receptor molecules (CD4/CD8) required BCR Recognition without requirement for co-receptor molecules Peptide T-cell receptor (TCR) Immunoglobulin (Ig)