Lecture 11 Flashcards
Types of specific Immunity.
- naturally acquired active: host develops after foreign substance exposure
- naturally acquired passive: transfer of Ab
- artificially acquired active: vaccination
- Artificially acquired passive: Ab formed by another host transferred to another.
Affinity
strength of which the antibody binds to the antigen at the proper site
Avidity
overall strength of the Ag-Ab binding. based on affinity and number of sites that are bound
Hapten
Ag that is super small, and combined with carrier molecules to act as an Ag
What cells are lacking MHC I?
RBC, cancer, virally infected cells
Endogenous Ag processing
consists of MHC I binding and presenting to CD8+ T cells
Exogenous Ag processing
consists of MHC II binding and presenting Ag fragments from the outside of the cell to CD4+ T cells
Antigen Presenting Cells (APC)
B cell, Dendritic cells, Activated macrophages
Natural killer cells have what function?
kill virus infected cells and tumor cells, attack parasites
What is a Th0 cell?
undifferentiated T cell
What is a Th1 cell?
helper cell that activates macrophages
What is a Th2 cell?
helps B cells to produce antibodies
What is a Th17 cell?
aid with microbial response; inflammation response
What is a Treg cell?
This cell aids with controlling the immune response; prevents a cytokine storm, or overactivation which would be deleterious to the self.
What do Th1 cells do?
promote Tc and activate macrophages.
- secrete IFN-gamma, IL-2, TNF-beta
What do Th2 cells do and secrete?
- stimulate antibody resposne; defend against helminths
- promote allergic reaction
- secrete IL-5,-6,-10,-13
When does a CD8+ T cell kill the target cell?
binds to target then activates perforin and CD95 pathway to cause lysis to the target cell.
What are the two signals that are required for T cell activation?
- TCR/MHC initiates the signaling cascade of membrane and intracellular molecules
- second signal activates proliferation, differentiation, gene expression of genes unique to the required response
What is teh function of Treg cells?
- suppress function of IL-9, TGF-beta
- IL-10 inhibits Th cell function
- Foxp3 upregulates CD25/CTLA-4 which are inhibitory signal receptors
What can be a superantigen?
bacterial or viral proteins
What are the effects of superantigen binding?
- nonspecific T cell activation
- massive, rapid release of cytokines
- cytokine storm, do not bind at the CDR3 domain like other Ag.
What two ways can B cells be activated?
- T cell dependent
2. T cell independent
What two signals are required for T cell dependent antigen activation?
- Ag-BCR complex binding
- Th2 cell binds with B cells’ Ag to secrete cytokines
- similar to T cells binding (2 signals at minimum)
What are the effects of B cells being activated by T cell?
- differentiation in to plasma cells or memory cells
What are the effects of T independent antigen activation?
- less effective than T cell dependent
- low affinity for Ag
- no memory B cells form
- bind to large number of epitopes
Features of IgG
- monomer
- fix complement
- blood, lymph, intestine
- enhance phagocytosis, neutralize toxins, protects fetus/newborn
Features of IgM
- fix complement
- blood, lymph, B cells
- agglutinate microbe, 1st Ag produced in infection.
Features of IgA
- dimer. secretory is slgA
- in secretions
- mucosal protection
Features of IgD
- monomer
- blood, lymph, B cells
- initiate immune response
Features of IgE
- on mast cells, basophils, blood
- provide opsonization
- allergic reactions, lyse helminths (parasitic worm)
What is generally secreted before and after activation of B cells?
before: monomeric IgM
after: pentameric IgM
What is an antibody titer?
- measure of serum antibody concentration
2. represents the lowest amount of antiserum that can be measured
What is unique about a second immune response, which utilizes memory cell?
- shorter lag phase
- more rapid log phase
- longer persistence
- higher IgG titer and Ab have higher affinity for Ag
What contributes to Ab diversity?
- combinatorial joining; junctional joining
- alternate splicing of mRNA
- somatic mutation
What is unique about combinatorial joining?
- segments are clustered separately on same chromosomes
- RAG-1,-2 enzymes are required
- heavy and light chain specific
What can somatic mutation cause, and where will they most likely happen?
- produce Ab with different epitopes
- therefore will occur on V regions
- high rate of somatic mutation with Ag challenge
What is a hybridoma?
monoclonal antibody
What are monoclonal antibodies, such as hybridomas, potentially going to be used for?
- overcome limitations of antisera
2. used to produce monoclonal Ab that recognize one epitope
What are the effects of Ab-Ag binding?
- agglutination
- opsonization
- complement activation
- neutralization
- antibody dependent cell-mediated cytotoxicity
What is agglutination?
- Ag-Ab binding effect
2. grouping of bacteria to localized areas
What is opsonization?
- Ag-Ab binding effect
2. coating of Ag with Ab to enhance phagocytosis
