Microbiology and Immunology 2500A/B Study Guide - Final Guide: Adaptive Immune System, Cytotoxic T Cell, Lymph Node
10 Jan 2017
School
Department
Professor
Adaptive Immunity
B-Cell Immunity
Main Defences In Adaptive Immunity
•B Cell Immunity = antibodies (important against extracellular pathogens)
•antibodies do not go inside of cells.
•T Cell Immunity = (important against intracellular pathogens)
•Helper T Cells (Th cells; CD4 + T cells)
•Cytotoxic T Cells (CTL; CD8 + T cells)
•Adaptive since immune response is more efficient with re-exposure to the same pathogen.
Recruits a larger and more faster immune response each time.
•This is the basis for vaccination. When you are re-exposed to pathogen, you have the
memory cells that will respond faster and with better magnitude.
•Small pox only needs one vaccination to be resistant for life. The antibodies for small box
have been detected 75 years after that one vaccine you are given as a child.
•Naive cells (because they have never seen the pathogen before) are responsible for the
induction of the adaptive immune response.
•Then, these naive cells become effector cells that are capable of going and destroying the
pathogen so they create the adaptive immune response.
•Memory B, Th, and CTL cells are left after the pathogen is destroyed to provide a more
effective response with subsequent exposures.
magnitude
of the
immune
response
Primary
Memory
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Lymphoid Tissues
•Adaptive immune system involves lymphoid tissues.
•Primary lymphoid tissues are where B and T cells develop. Arise from hematopoiesis.
•Bone Marrow (B,T) - B cells develop in bone marrow.
•Thymus (T) - T cells develop in bone marrow then thymus.
•T-Cell development: develop in bone marrow, then in thymus where naive helper T cells and
cytotoxic T cells enter circulation and are relocated to
the lymph nodes, spleen and MALT tissues.
•Thymus very large in newborns to produce many
naive T-cells, allows them to develop their own
adaptive immunity. All naive, so don’t have good
immunity yet.
•Elders have bad immunity because they have a
very small thymus.
•Secondary Lymphoid Tissues are where naïve B & T
cells meet/respond to pathogens and become
effector cells and memory cells.
•This is where adaptive immunity is initiated. These
tissues include:
•Lymph nodes (filters lymph) = site where naive B
and T cells meet lymph-borne pathogens.
•Naive B and T cells enter in through artery.
•B cell and T cell immunity are initiated in different areas in
the lymph nodes
•Spleen (filters blood) = site where naive B and T cells meet
blood-borne pathogens.
•Systemic infections are mounted against by immune
responses in the spleen.
•Mucosa-Associated Lymphoid Tissues (MALT) = tonsils,
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adenoids, appendix, Peyer’s patch of small intestine.
•= site where naive B and T cells meet pathogens in mucosal
areas. This includes the gastrointestinal, respiratory and
reproductive tracts.
Lymphatic System
1. Plasma enters tissues via capillaries = interstitial fluid.
2. Interstitial fluid enters lymphatic vessels = lymph.
3. Lymph filters through LYMPH NODES.
•Blood flowing out of heart and meet the tissue from capillaries. Plasma
will enter into the tissues from the capillaries and when it enters it is
called interstitial fluid. Will then exit the blood and enter
lymphatic vessels and is lymph. Lymph filters though lymph
nodes.
•LYMPH removes waste products (pathogens, dead cells, CO2)
from tissues.
•If tissue is infected, lymph transports pathogen by picking it up
and bringing it through the lymphatic system into lymph node
and adaptive immunity is initiated.
•In an intradermal vaccine (such as the flu shot), the injected pathogen is carried to the
lymph node via the lymph.
More Information on MALT tissues
•Mouth is the largest opening in the body, so provides an entrance for numerous pathogens.
•Adenoids & Tonsils (= MALT) guard entrance to GI tract and respiratory tract.
•In childhood, tonsils are often swollen due to infections from many “first time” pathogens
because mounting lots of adaptive immune responses.
T and B cell receptors
•T and B cells both express surface receptors.
Structure of B cell and T cell receptor:
• B cell receptor has 2 identical
heavy and light chains. Bound to
the surface of a B cell by
transmembrane region.
•T cell receptor has alpha and beta
chains.
•BCR/TCR have a variable region
and a constant region.
•BCR have two variable regions
and TCR have one variable region.
= Immunoglobin
molecule
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Document Summary
Recruits a larger and more faster immune response each time. Primary magnitude of the immune response: this is the basis for vaccination. When you are re-exposed to pathogen, you have the memory cells that will respond faster and with better magnitude: small pox only needs one vaccination to be resistant for life. Lymphoid tissues: adaptive immune system involves lymphoid tissues, primary lymphoid tissues are where b and t cells develop. This includes the gastrointestinal, respiratory and reproductive tracts. Lymphatic system: plasma enters tissues via capillaries = interstitial uid. 2: lymph lters through lymph nodes, blood owing out of heart and meet the tissue from capillaries. Interstitial uid enters lymphatic vessels = lymph. will enter into the tissues from the capillaries and when it enters it is called interstitial uid. Will then exit the blood and enter lymphatic vessels and is lymph. T and b cell receptors: t and b cells both express surface receptors.
