Ig's and Antigens Flashcards
What are the three roles of antibodies in immunity?
Neutralization
Opsonization
Complement fixation
What Ig is most prominent in serum?
IgG
Which Ig is most common in everything but serum?
IgA
What is agglutination?
aggregation of antigens by antibodies, which cause clumping
Which Ig causes agglutination?
IgM, recognize antigens (ABO groups) on RBCs and causes cell clumping and lysis
Why does Cold Agglutination Disease (CAD) occur?
passes through the acral blood vessels, the cooling IgM binds and agglutinates RBCs, activates complement
What’s the difference between primary and secondary Cold Agglutination Disease?
primary: idiopathic
secondary: due to underlying disease such as lymphoproliferative disorders, infection, or autoimmune disorder
_____________ CAD makes up 15% of autoimmune hemolytic anemias.
Primary
What’s the function of IgA?
mucosal immunity via neutralization
IgA monomer is located in _________
IgA dimer is ____________
monomer = serum dimer = secreted
Which antibody lives longest?
IgG
Which antibody is a pentamer?
IgM
Which antibody could be a dimer (most often), a monomer, or trimer?
IgA
Which antibody is least present in serum?
IgE
Function of IgD?
tolerance
expressed on surface of B cells
Why are IgE levels in serum low?
because IgE binds to FC-epsilon receptors on mast cells and basophils almost immediately after production
Which antibody is the primary response for agglutination?
IgM
Which two antibodies neutralize toxins/bacteria/viruses?
IgG and IgA
Which antibody functions in defense against parasites and hypersensitivity (allergy) reactions?
IgE
What is neutralization?
when antibodies prevent the adherence of toxins, bacteria, or viruses to the host
What is opsonization?
the antibody coats the target in order to promote an immune response
What are two methods of opsonization?
phagocytosis
antibody-dependent cell-mediated cytotoxicity (ADCC)
Which cells are involved in phagocytosis?
neutrophils, macrophages, and dendritic cells
Which cells are involved in ADCC?
NK cells and eosinophils
What are the four things that complement activation does?
enhances uptake
kills susceptible bacteria
promotes inflammation
attracts immune cells to the area
Which two antibodies activate the classical complement cascade?
IgM and IgG
Why is IgM so effective in agglutination?
It has 10 binding sites! (pentameric)
Which antibody function is the basis of passive immunization?
neutralization
IgG and IgA neutralize microbes and their toxins, which is used when someone needs protection against a virus emergently. The patient gets these antitoxin antibodies pumped into their system.
Fc receptors promote ________________ of opsonized targets
phagocytosis
What determines which cells react to antibodies?
Fc receptor expression on cell surface
FCgammaRI allows IgG to ________
activate phagocytosis
FCgammaRIII allows IgG to _____________
do ADCC
FCepsilonR1 allows IgE to __________
ADCC
- causes degranulation of mast cells to increase allergic response
the poly Ig receptor (pIgR) allows IgA to move where?
across the membrane
from lamina propria to lumen
What type of dendritic cell presents self-antigens to T cells?
A) Langerhan
B) Interdigitating
C) Follicular
Interdigitating
Located in thymus
What type of dendritic cells are APC’s to B cells?
Follicular
in lymphoid follicles
What type of dendritic cells are found in the skin?
Langerhan
When Langerhan’s take up antigen, they are ___________
immature
When Langerhans present antigen to T cells, they are _________
mature
