Immunoglobulins Flashcards
What is the function of Ig’s?
Opsonization - sends eat me signal to phagocytes
Neutralization of virus so virus can’t attach to host cells
What is the structure of Ig’s?
Y shaped polypeptide chain connected by disulfide bonds
2 heavy and 2 light chains - Each has constant and variable regions
What is the Fab?
Fragment binding area
Binds antigen epitope
Consist of variable heavy and light chains
What determines the antibody class?
Heavy chain determines IgG, IgA, IgM, IgD, or IgE
What is the Fc?
Fragment crystalizable
Consist of Constant Heavy chains
Ch2 binds complement
Ch3 binds to macrophage
What is the Hinge area?
Allows antibody to change from Y to T shape
Located between Ch1 and Ch2 regions
What is the Ig Supergene family?
Proteins that have a similar structure to Ig’s and come from the same ancestral gene
Include surface ag receptors, co-receptors, cell adhesion molecules, and cytokine receptors
What blood groups do enzymes destroy?
Duffy’s MN’S were destroyed
What is the effect of papain treatment?
2 Fab + 1 Fc
What is the effect of pepsin treatment?
1 Fab(2) + 1 Fc
What is electrophoresis?
Ig will migrate in an electical field
Albumin moves the fastest toward + pole
Gamma globulns migrate the slowest
Causes of polyclonal gammopahy
Chronic infection
Immune mediated disease
Liver disease
Causes of monoclonal gammopathy
Narrow spike of alpha, beta, or gamma globullin Multiple myeloma Waldenstrom's Macroglobulinemia Lymphoma Chronic lymphocytic leukemia
What are the characteristics of IgG antibodies?
y heavy chain half life = 23 days Has Gm and Km allotype Activates complement Cross placenta
What are the characteristics of IgM antibodies
u heavy chain half life = 5 days Km allotype activates C' Found on surface of B lymphs
What are the characteristics of IgA?
a heavy chain found in secretions can activate alternative C' monomeric or polymeric 30% of Anti-A and -B is IgA
What are the characteristics of IgD?
Delta heavy chain
found on surface of B cells
What are the characteristics of IgE?
Bound to basophils or mast cells
Binding of antigen triggers release of histamine
Involved in hypersenstivity - anaphylaxis and parasitic infections
Which IgG subclasses can activate complement?
IgG1 and IgG3
IgG2 can weakly or use alternative pathway
Which IgG subclasses can bind to Fc receptors on phagocytes?
IgG1 and IgG3
Which IgG subclasses can bind to staphylococcal Protein A
IgG1 and IgG2
+ some allotypes of IgG3
What subclass are Rh antibodies more commonly?
IgG1 and IgG3
What subclass are Kell and Duff antibodies?
IgG1
What subclass are Kidd antibodies?
IgG3
High complement function
Which IgG subclass causes severe HDFN?
IgG1
What IgG subclass is anti-CD47
IgG4 - some monoclonal antibodies don’t detect
Which IgG subclass has Gm?
IgG1, IgG2, + IgG3
How does Tango Anti-IgG work?
Well are coated with Staph Protein A which bind to Fc portions of IgG. Plasma is added, incubated, and washed. Anti-IgG is added and crosslink antibody bound to Staph A protein on wells. Positive = smooth layer cells. Negative = Cell button
Which IgG subclasses are considered clinically insignifcant?
IgG2 and IgG4 can’t bind to Fc receptors on Phagocytes so IgG coated cells will not be phagocytized
What are the three genes required for Ig production
Heavy gene located on Chromosome 14
Lambda gene located on Chromosome 22
Kappa gene located on Chromosome 2
What is gene rearrangement?
The Variable (V), Diversity (D), and Joining (J) segments combine in different ways to form new sequence that recognize different epitopes Each B cell can recognize only one antigen
What is Isotype switching?
Naive B cells only have IgM and IgD on their surface
Once activated B cell can begin to produce IgG or IgA
How is the Isotype determined?
Isotype = Class
Determined by the constant Heavy region
What is allotype?
Allotype may differ from person to person
Determined by Gm and Km
What is idiotype
Depends on the variable/hypervariable region of the antibody molecule
Located on Fab portion of antibody and provides ability to recognize different epitopes
Determined by gene rearragement
All antibodies that recognize the same epitope have the same idiotype regardless of class
What is Gm?
Genetic marker on heavy chain of IgG1, IgG2, IgG3
Gm is like an antigen on the the antibody and can make anti-Gm.
What is Km?
markers on Kappa light chain
What is Am?
Markers on IgA antibodies
