Transcript Receptori za antigen na limfocitima

Antigen Receptors of
Lymphocytes
Receptors for recognition
Innate immunity
Recognition: molecular patterns
Genes: functional, germline encoded
Presence: multiple copies of different
receptors
Distribution: non-clonal distribution
(same receptor on all cells within
a cell line and even on the
different lineages)
Aquired immunity (T i B lymphocytes)
Recognition : molecular details
(antigenic determinants)
Genes: functional after DNA recombination
Presence: multiple copies of the same
receptor
Distribution: clonal (cells within one
clone exhibites receptor of
the same specificity)
Antigen Receptors of Lymphocytes - Similiarity
Antibody (Immunoglobulin)
T-cell receptor(TCR)
Membrane Ig
Antigen presenting cell
On the lymphocyte membrane
Antigen Receptors of Lymphocytes - Similiarity
Ig domains
On the lymphocyte membrane
Members of the immunoglobulin superfamily (domain structure)
Antigen Receptors of Lymphocytes - Similiarity
On the lymphocyte membrane
Members of the immunoglobulin superfamily (domain structure)
Two different chains
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)
Antigen Receptors of Lymphocytes - Similiarity
Activation motif
Disulphide bond
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
Antigen Receptors of Lymphocytes - Differences
Antibody (Immunoglobulin)
Membrane Ig
T cell receptor (TCR)
Antigen presenting cell
Signal
trasduction
Recognizes:
Signal
trasduction
Recognizes :
Free and membrane antigens
Antigens on the other cell membrane
Protein, polysaccharide, lipid, DNA, RNA Peptides only (αβ TCR)
Conformational and linear epitopes
Linear epitopes
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)
Antibody
structure
Membrane
of the B-cell
Nobel prize for physiology and medicine
1972
Gerald M. Edelman
Rodney R. Porter
"for their discoveries concerning the chemical structure of antibodies"
Antibody structure
Antigen binding sites
Light chain
Light chain
Heavy chain
Heavy chain
Disulphide bonds
Antibody structure – papain digestion
Antibody
structure
Antigen binding
Hinge regionFab fragmentsPapain
Fc fragment
Interaction with other
participants in the immune
Response (cells, complement)
Antibody structure – pepsin digestion
Antigen binding
F(ab)2 fragment
Pepsin
T-cell receptor
Contact
amino acid
Polymorphic parts
of MHC molecule
Anchoring amino acids
MHC groove
Peptide
BCR
TCR
• Recognition without
• Co-receptor molecules (CD4/CD8)
requirement for co-receptor required
molecules
Immunoglobulin (Ig)
T-cell receptor (TCR)
Peptide