Immunology Flashcards
Where in the lymph node do B cells localize?
Localized in the follicle of the lymph node.
Primary follicles are in the outer cortex and are dormant.
Secondary follicles are in the center germinal centers and are very active.
What is found in the lymph node medulla?
Medullary cords and medullary sinuses.
Communicate with efferent lymphatics and contain reticular cells and macrophages.
What is found in the paracortex of the lymph node?
Houses T cells
This is the region between the cortex and follicles of the medulla.
B and T cells enter from the blood here and not well deveoped in DiGeorge syndrome.
Which part of the lymph node is not well developed in patients with De George syndrome?
Paracortex
In extreme immune responses, which part of the lymph node enlarges?
The paracortex
the right lymphatic duct drains what?.
The entire right side of the body above the diaphragm
The left lymphatic duct drain what?
Drains everything except for the right side of the body above the diaphragm.
EMPTIES INTO THE LEFT SUBCLAVIAN AND INTERNAL JUGULAR VEINS.
where are T cells found in the spleen?
These are found in the periarterilar lymphatic sheath within the white pulp of the spleen.
Where are B cells found in the spleen?
The follicles within the white pulp of the spleen.
what is the marginal zone in the spleen and what can be found here?
Marginal zone is between the red and white pulp containing the antigen presenting cells and specialized B cells.
they capture blood born molecules here.
Why is the spleen so important for encapsulated bacteria?
The macrophages in the spleen remove encapsulated bacteria.
Thus, when a patient misses a spleen they are at increased risks.
Howell jolly bodies, target cells, thrombocytosis, and lymphocytosis is all seen after…
After a splenectomy.
Howel jolly bodies are nuclear remnants
Thrombocytosis is loss of sequestration and removal
Lymphocytisis is loss of sequestration of lymphcytes.
what is the thymus important for?
Differentiation and maturation of T cells!
Which pharyngeal pouch does the thymus evolve from?
The third pharyngeal pouch.
From mesenchymal origin
What is found in the cortex of the thymus?
Immature T cells
Medulla is pale with mature T cells and hassall corpuscles containing epithelial reticular cells.
Which type of immunity relies on toll-like receptors for antimicrobial activity?
This is in innate immunity.
TLR’s recognize patterns (PAMPS)
such as LPS, flagellin and ssRNA.
What do MHC I cells bind?
TCR and CD8 on T killer cells.
these present through synthesized antigens
Where are antigen peptides loaded onto MHC I in the cell?
By the rough endoplasmic reticulum
What protein is associated with MHC I ?
B2 microglobulin
What cells present MHC II?
Antigen presenting cells present exogenously synthesized antiges to CD4 helper T cells.
What cells read MHC II?
CD4 T cells.
How do natural killer cells work?
Work by using perforin and granzymes to induce apoptosis.
What upregulates natural killer cells?
IL-2
IL-12
IFN-alpha
IFN Beta
What do CD4 cells do?
CD4 helper T cells help to make B cells compose antibodies
What is positive selection of T cells?
Thymic cortex, T cells that express TCRs capable of BINDING SELF MHC molecules survive.
What is negative selection of T cells?
Thymic medulla
T cells express TCRs with high affinity for self antigens undergo apoptosis.
Where does positive selection of T cells occur?
In the thymic cortex
Where does negative selection of T cells occur?
In the thymic medulla.
What do TH1 cells secrete to activate macrophages?
TH1 secretes interpheron gamma to activate macrophages and CD8 cells.
What cytokines activate TH1 cells?
IFN gamma and IL-12
IL-4 and IL-10 from TH2 cells deactivate TH1 cells.
What cytokines are secreted by TH2 cells?
IL-4
IL-5
IL-10
IL-13
What do TH2 cells do?
Recruit eosinophils for parasite defence and promotes IgE production by B cells
What activates TH2 cells?
IL-4
What inhibits TH-2 cells?
IFN gamma from TH1 cells.
what do macrophages release to stimulate T cell differentiation to TH1 cells
Release IL-12
REMEMBER TH1 CELLS RELEASE IFN-GAMMA TO ACTIVATE MACROPHAGES.
THEY ACTIVATE EACHOTHER.
What do regulatory T cells do?
These supress CD4 and CD8 T-cell functions.
Express CD3, CD4, CD25, and FoxP3.
Which cytokines activate regulatory T cells?
IL-10
TGF-Beta
Which other two surface molecules interact when CD4 and CD8 cells read an antigen presenting cell?
B7 and CD28
Which other two surface molecules interact when a T helper cell turns on a B cell?
CD40L on the helper and CD40 on the B cell.
think the ligand has to fit on the receptor. Thus it makes sense that the helper has the ligand.
What is the Fab region of immunoglobulins and what are they composed of?
These are the variable region of the antibody.
Composed of two light chains and four heavy chains.
The heavy chain is part of the Fc region and the Fab region.
The light chain is only in the Fab region.
What is unique about the Fc region of an immunoglobulin?
It is constant
Has Carboxy terminals
Complement binding and carbohydrate side chains.
Which immunoglobulins are present on all mature B cells?
IgM and IgD
After entering the germinal centers of lymph nodes they can isotype switch
What is the most abundant immunoglobulin in the serum
IgG fixes compliment and can cross the placenta
Which immunoglobulin can cross the placenta?
IgG
What does IgA do?
prevents bactera and virus attachment to mucus membranes.
DOES NOT FIX COMPLIMENT. serves as a monomer in the serum and dimer when secreted.
which antibody is found in secretions or breast milk?
IgA
Most overall created immunoglobulin but lowest serum levels.
Which immunoglobulin is produced in the immediate response to an antigen?
IgM
How does IgE work?
Binds mast cells and basophils cross linked when exposed to the allergen.
Mediates type 1 hypersensitivity through histamine release
Also allows resistance to eosinophils.
Lowest concentration in the serum.
Whats the difference between thymus independent antigens and thymus dependent antigens?
Independent antigens do not have protein bodies that the immune response can react to.
Dependent antigens then do have protein bodies that the immune response reacts to.
Which cytokine leads to the release of acute phase reactants?
IL-6
how does C-reactive protein work?
Fixes compliment to facilitate phagocytosis
Measured clinically as an ongoing form of inflammation.
What is the role of ferritin during an infection?
Ferritin binds and sequesters iron from the use of pathogens.
what does hepcidin do?
Inhibits the absorption of iron from the gut bound to ferritin.
seen in chronic infections.
Why is albumin downregulated during infections?
Reduction conserves amino acids for positive reactants.
How does the classic pathway of complement work?
Works by working with IgG and IgM
How does the alternative compliment pathway work?
Recognizes microbe surface mollecules
How does the lectin complement pathway work?
Recognize mannose or other sugars on the microbe surface.
Which complement factor recruits neutrophils?
C5a
C3a and C4a promote anaphylaxis
what happens if there is a C1 esterase inhibitor deficiency?
Causes hereditary angiodema
ACe inhibitors are contraindicated (fat lady with lip ring)
What happens with C3 deficiency?
Increases risk of severe recurrent pyoenic sinus and respiratory tract infections.
Increase Type III hypersensitivity risk.
what happens when there is a C5-C9 deficiency?
Terminal complement deficiency increases susceptibility to neisseria bacterimia.
What does IL-1 do?
Upregulates fever and acute infammation.
What does IL-6 do?
Causes fever and stimulates acute phase protein release
What does IL-8 do?
Major chemotactic factor for neutrophils!
What does IL-12 do?
Induces differentiation of T cells into TH1 cells
Also activates NK cells.
Released from macrophages.
What does TNF alpha do?
Mediates septic shock
Activates endothlum
What does IL-2 do?
Stimulates frowth of helper, cytotoxic, and Treg cells as well as NK cells.
What does IL-3 do?
Supports growth and differentiation of bone marrow stem cells much like GM-CSF.
What does IFN gamma do?
Secreted by NK cells in response to macrophage IL-12 causing macrophages to kill phagocytosed organisms.
What does IL-4 do?
Induces TH2 differentiation promoting B cell frowth an switching classes to IgE and IgG
What does IL-5 do?
Switches to IgA stimulates eosinophil growth.
What does IL-10 do?
Modulates the inflammatory response decreasing MHC II and TH1 expression.
TGF-B and IL-10 both attenuate the immune response. Both secreted by T-reg cells.
Hot T-bone stEAK
Il-1 Fever (hot) IL-2 T cells IL-3 bone marrow IL-4 IgE IL-5 IgA IL-6 Akute phase protein production
What is the NADPH oxidase complex utilized for?
Respiratory burst (oxidative burst) to kill pathogens.
Which type of organisms are patients at risk for if they dont have a functioning NADPH oxidase?
Catalase positive species.
What is the defensive purpose of IFN alpha and IFN beta?
These are both antivirals and part of teh innate defence
what is Anergy?
State during which a cell cannot become activated by exposure to an antigen
T and B cells become anergic when exposed to their antigen without a costimulatory signal. This is a form of self tolerance.
How does Super toxic shock syndrome work?
Cross link Beta region of the T cell to the MHC II on APCs activating and CD4 and leadin to a cytokine storm.
What is passive immunity?
preformed antibodies working against the antigen.
Giving someone an antitoxin (immunoglobulin injection) is a form of passive immunity.
What is active immunity?
Slow long lasting protection of memory, goes through B cell activiation.
Name the four types of hypersensitivity
“ACID”
Type 1 : anaphylaxis via IgE on mast cells rapid reaction. leukotriens produce delayed following resposne.
Type 2: Cytotoxic via IgM and IgG
Type 3: Immune complexes think serum sickensses
Type 4: Delayed response mediated by T cells. Transplant rejections, TB tests, contact dermatitis from touching plants. DOES NOT INVOLVE ANTIBODIES
What is a direct coombs test?
Tests for antibodies that have adhered to a patients RBC’s
What is an indirect coombs test?
Tests for serum antibodies that can adhere to other RBC’s
What is an arthus reaction?
Local subacute antibody medated Type III hyersensitivity after injections.
