nullImmunoglobulins:
Structure and FunctionImmunoglobulins:
Structure and FunctionImmunoglobulins:Structure and FunctionImmunoglobulins:Structure and FunctionDefinition: Glycoprotein molecules that are produced by plasma cells in response to an immunogen and which function as antibodiesGeneral Functions of ImmunoglobulinsGeneral Functions of ImmunoglobulinsEffector functions
Fixation of complement
Binding to various cells(Usually require Ag binding)Ag binding
Can result in protection
ValencyBasic Immunoglobulin StructureBasic Immunoglobulin StructureImmunoglobulins - heterogeneous
Myeloma proteins - homogeneous immunoglobulinsImmunoglobulin StructureImmunoglobulin StructureHeavy & Light Chains
Disulfide bonds
Inter-chain
Intra-chainImmunoglobulin StructureImmunoglobulin Structure
Variable & Constant Regions
VL & CL
VH & CH
Hinge RegionImmunoglobulin StructureImmunoglobulin StructureDomains
VL & CL
VH & CH1 - CH3 (or CH4)
OligosaccharidesIgG moleculeIgG moleculeUsed with permission from: Dr. Mike Clark, Immunology Division, Department of Pathology Cambridge University, Cambridge, EnglandStructure of the Variable RegionStructure of the Variable RegionHypervariable (HVR) or complimentarity determining regions (CDR)Framework regionsImmunoglobulin Fragments: Structure/Function RelationshipsImmunoglobulin Fragments: Structure/Function RelationshipsFab
Ag binding
Valence = 1
Specificty determined by VH and VLFc
Effector functionsImmunoglobulin Fragments: Structure/Function RelationshipsImmunoglobulin Fragments: Structure/Function RelationshipsImmunoglobulin Fragments: Structure/Function RelationshipsImmunoglobulin Fragments: Structure/Function RelationshipsFab
Ag binding
Fc
Effector functions
F(ab’)2Human Immunoglobulin ClassesHuman Immunoglobulin ClassesIgG - Gamma () heavy chains
IgM - Mu () heavy chains
IgA - Alpha () heavy chains
IgD - Delta () heavy chains
IgE - Epsilon () heavy chainsHuman Immunoglobulin SubclassesHuman Immunoglobulin SubclassesIgG Subclasses
IgG1 - Gamma 1 (1) heavy chains
IgG2 - Gamma 2 (2) heavy chains
IgG3 - Gamma 3 (3) heavy chains
IgG4 - Gamma 4 (4) heavy chains
IgA subclasses
IgA1 - Alpha 1 (1) heavy chains
IgA2 - Alpha 2 (2) heavy chainsHuman Immunoglobulin
Light Chain TypesHuman Immunoglobulin
Light Chain TypesKappa ()
Lambda ()Human Immunoglobulin
Light Chain SubtypesHuman Immunoglobulin
Light Chain SubtypesLambda light chains
Lambda 1 (1)
Lambda 2 (2)
Lambda 3 (3)
Lambda 4 (4)ImmunoglobulinsImmunoglobulinsNomenclature
IgM (kappa)
IgA1(lambda 2)
IgG
HeterogeneityIgGIgGStructure
Monomer (7S)IgGIgGStructure
Properties
Major serum Ig
Major Ig in extravascular spaces
Placental transfer – Does not require Ag binding ( IgG2)
Fixes complement ( IgG4)
Binds to Fc receptors ( IgG2, IgG4)
Phagocytes - opsonization
K cells - ADCCIgMIgMStructure
Pentamer (19S)
Extra domain (CH4)
J chainIgMIgMStructure
Properties
3rd highest serum Ig
First Ig made by fetus and B cells
Fixes complementnullFixation of C1 by IgG and IgM AbsNo activationActivationIgMIgMStructure
Properties
3rd highest serum Ig
First Ig made by fetus and B cells
Fixes complement
Agglutinating Ig
Binds to Fc receptors
B cell surface IgB Cell Antigen Receptor (BcR)B Cell Antigen Receptor (BcR)IgAIgAStructure
Serum - monomer
Secretions (sIgA)
Dimer (11S)
J chain
Secretory componentOrigin of Secretory Component of sIgAOrigin of Secretory Component of sIgAIgAIgAStructure
Properties
2nd highest serum Ig
Major secretory Ig (Mucosal or Local Immunity)
Tears, saliva, gastric and pulmonary secretions
Does not fix complement (unless aggregated)
Binds to Fc receptors on some cellsIgDIgDStructure
Monomer
Tail pieceIgDIgDStructure
Properties
4th highest serum Ig
B cell surface Ig
Does not bind complementIgEIgEStructure
Monomer
Extra domain (CH4)IgEIgEStructure
Properties
Least common serum Ig
Binds to basophils and mast cells (Does not require Ag binding)
Allergic reactions
Parasitic infections (Helminths)
Binds to Fc receptor on eosinophils
Does not fix complement