Humoral Immune Response Flashcards
What type of humoral response is by immunoglobulins produced in another animals
Passive adaptive
What type of humoral immunity is produced by ingesting colostrum
Passive natural
What type of humoral immunity occurs when an animal has acquired a disease and produces its own antibodies?
Active natural
What type of humoral immunity occurs when an animal is injected with a vaccine?
Active artificial
BCR and antibodies belong to the _______________________ of receptors
Immunoglobulin superfamily
B lymphocyte receptors are composed of _______ and ________ chains
Light and heavy
The ____________ region of the antibody binds antigen and is made up of both light and heavy chains
Variable
What are the 5 types of heavy chains, and what antibody to they correspond to?
a - IgA y - IgG Delta - IgD E - IgE u - IgM
Within the variable regions of BCR, what are the two regions?
Hypervariable regions (aka complementarity determining regions CDR))
Framework regions
The variable region of the BCR is folded so the _______________ region forms the antigen binding site
Hypervariable region
Complementarity-determining regions (CDR)
The heavy chain of the BCR of a, y, and delta have how many constant domains within the variable region?
3
CH1, CH2, CH3
The heavy chain of the BCR of u and E have how many constant domains within the variable region?
4
CH1, CH2, CH3, CH4
What is the function of the constant domains of the variable regions of BCR?
Stabilize the antigen binding site
Antibodies contain a _________ region that allows the movement binding regions which increases its interaction with antigens
Hinge region
One BCR can bind how many antigens?
2
A BCR signal is transduced into the cell by ?
CD79
The __________co-receptor of B lymphocytes binds to C3d on the antigen and transmits a signal through ___________ to enhance B cell response
CD21; CD19
________ helper T cells are involved in the humoral response by producing what 4 interleukins?
TH2
IL4, IL5, IL6, and IL13
____________ from TH2 stimulates growth and differentiation of Bcells, increased expression of MHCII, and induce Ig class switching
IL4
________ from TH2 cells stimulates Bcell differentiation into plasma cells, IgM and IgG production, selective IgA production, and in combination with IL4 stimulates IgE production
IL5
______ from TH2 is required for the final differentiation of plasma cells, combination with IL5 induces production of IgA, and combination with IL1 induces IGM production.
IL6
_______ from TH2 is required for optimal induction of IgE
IL13
Binding of what co-stimulators molecules between TH2 and APC leases to IL4 production and B cell proliferation
CD154 (TH2) bound to CD40 (Bcell)
Bcells undergo somatic mutation as they respond to antigen presentation. If the mutation reduced their antigen binding ability they will undergo __________
Apoptosis
What is the serum concentration of the 5 antibodies from greatest to least
IgG IgM IgA (in saliva, milk, and GI fluids) IgD IgE
Where are IgG antibodies produced??
Plasma cells in spleen, lymph nodes, and bone marrow
What functions do IgG perform in humoral immunity?
Inflammation
Agglutination
Opsonization
Activate classical complement pathway
What is the structure of IgM as a soluble antibody and as a BCR?
BCR - monomer attached to cell membrane
Antibody - pentamer linked by J chain (polypeptide)
All IgM have an additional constant region (CH4)
IgM is the primary antigen produced in the ____________ immune response. What are its functions?
Primary immune response
Opsonization
Virus neutralization
Agglutination
Not important to inflammation
What is the structure of IgA?
Dimer of antibodies linked by J chain; secretory component
Where is IgA found?
Body surface secretions: intestine, respiratory, urinary, skin, and mammary glands
(Transported through intestinal epithelial cells to external secretions)
Where is IgE produced ?
Plasma cells located under body surfaces
What is the structure of IgE
Typical Ig with additional content region (CH4)
___________ antibody is attached to the FceRI on mast cells and basophils
IgE
What is the function of IgE?
Inflammation
Release of inflammatory molecules from mast cells
Type 1 hypersensitivity
Parasite
IgD is not present in what species?
Cat, chicken, and rabbit
Where are IgD found and what is its main action?
Mainly attached to Bcells
Circulating IgD can bind to basophils
Mediate link between innate and adaptive immune response
What is the difference between isotype, allotype, and idotype?
Isotype- class of antibody (eg IgG or IgA)
Allotype - genetic differences in a molecule between members of the same species (IgG (A1) or IgG (A2))
Idiotype - unique differences between antibodies of different antigen binding specificities, determined by the variable region
Describe gene recombination that leads to expression of different antibody types
Gene contains variable regions and constant regions
variable regions are linked with the appropriate constant regions by gene recombination and deletion of intervening sequences that are not required
Gene with variable region and constant region exon
RNA splicing removes introns
Translation to protein
Naive B lymphocytes express what two classes of membrane bound antibodies that function as antigen receptors?
IgD and IgM
What is affinity maturation?
Repeated exposure to a protein antigen results in the production of antibodies with increasing affinity for the antigen
How do B and T cells enter the lymph node from the blood vessels
High endothelial venues (HEV) have receptors for cell-surface proteins of T and Bcells.
Bind receptors -> cell extravasate into the lymph node
What occurs in the lymph node that leads to activation of Bcells?
dendritic cells present antigen on MHC to Th2 cells
Th2 cells produce cytokines - IL4, IL5, IL6, IL13
Bcells activated
Bcells can function as antigen presenting cells. What is the process of antigen presentation and what co-receptors are involved?
Bcell phagocytose antigen bound to BCR
Antigen processed and presented on MHC II to a Tcell
CD4 of Th cell binds MHC II
CD28 (Tcell) bound to B7(Bcell)
CD40L (Tcell) bound to CD40 (Bcell)
What cells are present in the germinal center of the lymph node
Dividing Bcells make up centroblast
Resting Bcells make up centrocytes
Follicular dendritic cells
Surrounded by Th cells
What are produced from the germinal centers that leaves the lymph node in the efferent vessel?
Plamsa cells ->bone marrow
IgM excreted from plasma cells in the medullary cord (primary immune response)
What are the effector mechanisms of antibodies for bacterial toxins?
Neutralization
Bacterial toxin wants to bind cell receptors
Antibody binds the toxin to prevent binding –> phagocytosis by macrophage
What is the effector mechanism for bacteria in the extracellular space?
Opsonization
Antibodies bind bacteria
Macrophage binds Fc region of antibody –> phagocytosis
What is the effector mechanism for antibodies against bacteria in plasma?
Complement activation
Antibody bound to bacteria and activates complement pathway
Ingestion and lysis
How is diversity of variable regions of antibodies achieved?
Gene recombination
Somatic mutation
Gene conversion
What are the two light chain loci, located on different chromosomes?
Kappa
Lambda
How are unwanted genes deleted in gene recombination?
Looping out
Form a loop to bring desired genes together, recombinase cuts and joins ends.
Loop is excised and destroyed
What the steps of gene recombination to leading to a compete light chain protein??
DNA rearrangement -> join V and J genes
Transcription -> mRNA
MRNA -> splice to remove introns (V, J, and C regions)
Translation -> protein
Each B cell has _____ attempts to make a functional gene rearrangement
4
2 rearrangement with kappa chain
2 rearrangements with lambda chain
The variable regions (CDR) of TCR are formed by __________________ . Bcells have 3 different CDR’s, CDR1 and CDR2 are generated by ___________ and CD3 is generated by __________
Gene conversion; somatic mutation, gene conversion
How are Bcell somatic mutants selected?
Based on antigen affinity
Bcells that bind antigen strongly are stimulated while those that weakly bind undergo apoptosis
