Humoral Immune Response II Flashcards
Naive B lymphocytes express two classes of membrane bound antibodies
IgM and IgD
One activated B cell may generate up to ___ plasma cells
4,000 which can produce 10^12 antibodies per day
How many antibodies produced per second in plasma cell?
10,000
Repeated exposure leads to an increased
affinity for the antigen–> immune response becomes for efficient
The better the fit b/t antibody-binding site and antigen, the…
higher the affinity
BCR and complement receptor
bind to fragments of compliment proteins and deliver an additional signal to the B-cell nucleus
When a B cell doesn’t find a antigen or appropriate Th cell, it leaves the node and moves on the the next node via
efferent lymphatics
B cells and Th cells enter lymph node through
HEV’s and interact to effect B cell activation
Triggers response or carries antigen to secondary lymphoid organs
dendritic cells. Th2 humoral
B cells phagocytize antigen and fragments it, presented in MHC II and recognized by T cell receptor. What recognizes MHC II?
CD4
Where do B cells proliferate?
lymph nodes and germinal centers
germinal center forms from
primary lymphoid follicles
Dividing B cells are called
centroblast
Resting B cells are called
centrocytes
Germinal centers contain
Th cells and follicular dendritic cells
What are the type of cells that differentiate from B cells?
plasma and memory
Plasma cells leave through
efferent lymphatics
Plasma cells produce antibodies. ___ in primary immune response
IgM
In secondary antibody response, we have participation of memory B cells so the response is quicker and stronger. ___ in secondary immune response
IgG
Neutralization
bacterial toxins, neutralized & then phagocytized
Opsonization
whole membrane is covered w/ antibody
-phagocytic cells have Fc receptor to recognize antibody and ingest & lysis of bacteria
Complement activation
Bacteria in plasma, activated on pathogen IgG or IgM, ingestion & lysis
The ability of a receptor to bind to an antigen is determined by the ____
shape of its binding site
The info needed to make all proteins, including antigen receptors is in the
genome of plasma cells
Mammals could express up to 10^15 different antigen binding receptors on
B & T cells
-they use fewer than 500 genes!!!
Antibodies are proteins which are made up of
amino acids that can make shapes
Several genes code for the ___ while one gene codes for the ___
variable, constant
Gene diversity
gene recombination, somatic mutation, gene conversion
Antigen receptor chains are coded for by
3 genes from separate groups
Gene recombination
- one gene from each light and heavy chain selected
- IgK(kappa) IgL(lambda)
- Deleting unwanted genes that aren’t selected
- during B cell development, each cell has 4 attempts to make a productive gene rearrangement coding for a functional immunoglobulin.
- If it fails the 4th time–> APOPTOSIS
Somatic Mutation
- occurs on B cell receptors or antibodies
- difference b/t variable region of TCR and immunoglobulins is CDRs
- TCR-no somatic mutation
- Immunoglobulin light chain-somatic mutation or gene conversion
Immunoglobulins have ____ CDRs
3
How many bases encode for one amino acid?
3
Somatic mutation 1
reduced antigen binding –> apoptosis
Somatic mutation 2
enhanced antigen binding
- 3 reduced antigen binding–> apoptosis
- 4 advanced antigen binding–> clonal expansion
Gene conversion
- insertion of group of genes on variable region
- segments of upstream genes or pseudogenes are inserted into a single V region to generate diversity
T cell Receptor
- only gene cell recombination in variable region
- The basic structure of the 3 gene loci that code for the 4 diff TCR chains. The genes for beta chains are embedded w/in the alpha chain genes to form a single locus
- all variability and specifity come from selection of the genes
every time plasma cells divide they get
higher affinity
