Immunoglobulins Flashcards
Immunoglobulins
molecules (as a whole) that bind to antigens
antibody
recognize and bind to SPECIFIC antigens
affinity
degree of fit b/n Abs and Ags.
strength of binding
specificity
Abs bind to specific Ag that stimulated their production
cross-react
when Ab binds (@ lower affinity) to Ags other than their original, specific one.
neutralization
binds & prevents attachment to cell receptors
Structure of Abs
heavy chains (VH, CH1, CH2, CH3) light chains (VL, CL)
Antigen binding site
VH, VL of the Fab fragments
Fab
Fragment that Ag binds to. don’t crystalize.
domains = VH, CH1, VL, CL
Does NOT determine Ab function.
F(ab’)
both pieces of Fab for one Ab
Fc
constant fragment. Ag does NOT bind here. crystallizable.
DOES determine Ab function
Classes of Immunoglobulins
IgG, IgE, IgM, IgA, IgD
how are immunoglobulin classes determined?
by their heavy chains. (different genes in heavy chain gene complex)
IgG
Functions: BCR, Neutrailization, Complement, Opsonization, ADCC
Location: plasma, tissue fluids
Made in: spleen, lymph nodes of skin, & parenchymatous organs
Plasma [ ]: 1000-2000 mg/dL (HIGH)
IgM
Function: BCR, Neutralization, Complement
Location: Plasma
Made in:
Plasma [ ]: 50-200 mg/dL (LOWER)
IgA
Function: BCR, Neutralization
Location: secretions, plasma
Made in:
Plasma [ ]: 10-150 (LOWER)
IgE
Function: BCR, ADCC, Mast cell activation
Location: Mast Cells
Made in:
Plasma [ ]: 1-5 mg/dL (VERY LOW)
Functions of Immunoglobulins
- Ag Receptor (BCR)
- Neutralization
- Complement Activation
- Opsonization
- ADCC (Antibody-Dependent Cellular Cytotoxicity)
- Mast Cell Activation
Antigen Receptor on B cells
IgG, IgM, IgE, IgA, (IgD)
Abs on B cell plasma membranes that can be released (except for IgD) into the body once Ags bind. These then go initiate T-cell response
Neutralization
IgG, IgM, IgA
bind & prevent attachment to cellular receptors.
- inhibit effect of microbial toxins by blocking binding
- inhibits infectivity of viruses by blocking binding
- inhibits attachment of bacteria, fungi, & protozoa to epithelial cells
Complement activation
IgM > IgG
initiates classical pathway of complement activation
1 IgM binds to activate where as multiple IgG must bind to activate
Opsonization
IgG»_space; IgM
Ag binds to infectious agent and to receptors on phagocytes (Fc receptors) to enhance phagocytosis
Antibody-Dependent Cellular Cytotoxicity
IgG, IgE
when pathogens are too lg. to be internalized by 1 phagocyte, FcRs bind to IgG on pathogen & release lysosomal enzymes & ROI onto pathogen surface.
Eosinophils participate.
Mast Cell Activation
IgE
Ag binding to IgE on mast cells activate them & they release granules. works to our disadvantage when it reacts to allergens.
Antiserum, antisera
serum taken from animal that was actively immunized for particular antigen
antitoxin
antiserum produced to neutralize a toxin
antivenim
antiserum produced to neutralize snake venom
polyclonal response
many clones of B-cells producing antibodies that react with many epitopes.
serum taken from diff. animals may be diff
monoclonal antibodies
- derived from single clone of B cells & react w/ single epitope
- can be produced more consistently & cleanly
- can be fragmented & only the Fab region used to diminish Ab response
problems with passive immunization
- Immunoglobulins are proteins.
- proteins are good antigens.
- Immunoglobulins from 1 species given repeatedly to animals of diff. species induce Abs (antiglobulins) that reduce their effectiveness as therapeutic agents.
Preventable Fraction
1-(% Vaccinates Affected/% Controls Affected)
Prevention of infection
products able to PREVENT all colonization or replication of challenge organism
prevention of disease
products highly effective in preventing clinical disease
aid in disease prevention
products shown to prevent disease by a clinically significant amt that’s less than that required to prevent disease
aid in disease control
products that alleviate disease severity, reduce disease duration, or delay disease onset.
other claims (on vaccine labels)
products w/ beneficial effects other than disease control
Forces responsible for Ab binding to epitope
electrostatic forces, hydrogen bonds, Van der Waals forces, hydrophobic forces
IgA transport across membrane
- Binding of IgA to receptor on basolateral face of epithelial cell
- Endocytosis
- Transcytosis of apical face of epithelial cell
- Release of IgA dimer at apical face of epithelial cell.
