Antigen Receptors of Lymphocytes. Recognition: molecular patterns Recognition : molecular details...
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Transcript of Antigen Receptors of Lymphocytes. Recognition: molecular patterns Recognition : molecular details...
Antigen Receptors of Lymphocytes
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
Antigen Receptors of Lymphocytes - Similiarity
On the lymphocyte membrane
Membrane Ig Antigen presenting cell
Antibody (Immunoglobulin) T-cell receptor(TCR)
Antigen Receptors of Lymphocytes - Similiarity
On the lymphocyte membraneMembers of the immunoglobulin superfamily (domain structure)
Ig domains
Antigen Receptors of Lymphocytes - Similiarity
On the lymphocyte membraneMembers of the immunoglobulin superfamily (domain structure)Two different chains
Antigen Receptors of Lymphocytes - Similiarity
On the lymphocyte membraneMembers of the immunoglobulin superfamily (domain structure)Two different chainsVariable domains in contact with antigen (encoded by recombined DNA)
Antigen Receptors of Lymphocytes - Similiarity
On the lymphocyte membraneMembers of the immunoglobulin superfamily (domain structure)Two different chainsVariable domains in contact with antigen (encoded by recombined DNA) Associated signal transduction molecules
Activation motif
Disulphide bond
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, RNAConformational and linear epitopes
Recognizes :Antigens on the other cell membranePeptides only (αβ TCR)Linear epitopes
Antigen Receptors of Lymphocytes - Differences
Recognizes: Free and membrane antigens Protein, polysaccharide, lipid, DNA, RNAConformational and linear epitopesConsists of:4 polypeptide chains (2H and 2L)
Recognizes: Antigens on the other cell membranePeptides only (αβ TCR)Linear epitopesConsists of:2 polypeptide chains (αβ or γδ)
Antibody structure
Membrane of the B-cell
"for their discoveries concerning the chemical structure of antibodies"
Gerald M. Edelman Rodney R. Porter
Nobel prize for physiology and medicine 1972
Antibody structure
Heavy chain
Light chain Light chain
Heavy chain
Disulphide bonds
Antigen binding sites
Antibody structure – papain digestion
Hinge region PapainFab fragments
Fc fragment
Interaction with other participants in the immune Response (cells, complement)
Antigen bindingAntibody structure
Antibody structure – pepsin digestion
Pepsin
F(ab)2 fragment
Antigen binding
MHC groove
Anchoring amino acids
Contact amino acid
Peptide
Polymorphic partsof MHC molecule
T-cell receptor
TCR• Co-receptor molecules (CD4/CD8)
required
BCR• Recognition without
requirement for co-receptor molecules
Peptide
T-cell receptor (TCR)Immunoglobulin (Ig)