Immunology Flashcards
What is the difference between first-degree and second-degree immune organs?
First-degree: where immune cells develop (i.e., bone marrow and the thymus)
Second-degree: where immune cells are assisted (spleen, lymph nodes, tonsils, Peyer patches)
True or false: lymph nodes typically have more afferent vessels than efferent vessels.
True.
What is the main role of the lymph node medulla?
To communicate with the efferent lymphatic; medullae are typically T cells, B cells, and macrophages
Which part of the lymph node is likely to be impaired or underdeveloped in children with DiGeorge?
The paracortex
The superficial inguinal lymph nodes drain everything below the umbilicus with a few exceptions: ________________.
the testes, ovaries, and uterus drain into the para-aortic lymph nodes; the posterior calf and dorsolateral foot drain into the popliteal lymph nodes
T cells and B cells reside in which parts of the spleen?
T cells: periarteriolar lymphatic sheath
B cells: germinal centers
Where do macrophages catch encapsulated bacteria in the spleen?
In the marginal zone between the red pulp (RBCs) and white pulp (T cells and B cells, depending on the kind of white pulp)
What mechanism leads to immune vulnerability in post-splenectomy patients?
Decreased production of IgM –from decreased germinal centers –results in decreased complement activation, and complement activation is needed to kill encapsulated organisms.
What labs and histologic exams might you see in someone without a spleen?
Target RBCs
Lymph- and thrombocytosis (because they are normally sequestered in the spleen in a healthy person)
Howell-Jolly bodies (bits of DNA in RBCs normally removed by macrophages in the spleen)
Thymomas are associated with what two disorders?
Myasthenia gravis (no idea why) and superior vena cava syndrome
C-reactive protein is produced in response to _________. What does it do?
IL-6; it binds to dying cells –both human and bacterial – and stimulates the complement cascade to help get rid of cellular debris
One more time: which is MHC II, HLA-B or HLA-DR?
HLA-DR (“Two letters”)
True or false: MHC I is present on all cells.
False. It is not present on RBCs.
Which HLA types are associated with lupus?
D2 and D3 (“2 and 3 for S-L-E”)
Describe the maturation of T cells.
1) Bone marrow
2) Thymus cortex; CD4 and CD8 positive (positive selection: making sure it fits MHC)
3) Thymus medulla; CD4 or CD8 positive (negative selection: making sure it doesn’t recognize self-antigen)
4) Lymph node paracortex
Tonic expression of ___________ near M cells allows for development of Treg. Addition of __________ stimulates development of Th17.
TGF-beta; IL-6
IL-_____ down regulates Th1.
10 (produced by Treg)
Expression of the ________ gene is crucial during negative selection.
AIRE (because this causes thymic expression of proteins found throughout the body, thus ensuring that developing T cells can see all of the self-antigens)
Which interleukin stimulates development of Th2?
IL-4
Again, which interleukin stimulates Th1?
IL-12 (“twelve men to convict one prisoner”)
IL-12 is released by macrophages.
Describe the positive feedback between T cells and macrophages.
Macrophages secrete IL-12 which activates Th1 cells, and then Th1 cells secrete IFN-gamma which activates macrophages.
______________ kill cells with perforins and granzymes.
CD8+ T cells and NK cells
Which receptors do Tregs possess?
CD3, CD4, CD25, and FOXP3
(You already know the first two because they’re helper T cells, and you can use these mnemonics to recall the last two: 2x5 = 10, and Tregs secrete IL-10; and you need to be “cool as a fox” to help calm down your immune response.)
Diabetes in a male infant accompanied with dermatitis might be signs of _______________.
IPEX
Immune dysregulation, Polyendocrinopathy, Enteropathy, X-linked
A defect in the FOXP3 receptor that would normally allow Tregs to calm the body down.
The heavy chain contributes to ______________ and the light chain contribures to _______________.
the Fc and Fab regions; the Fab region
Why should you remember the Cs when it comes to the Fc region?
Complement binding
Constant
Carbohydrate side chain
Carboxy terminus
True or false: naive B cells express only IgD.
False. They express both IgM and IgD.
The complement-fixing antibodies include _______.
IgG and IgM
IgA circulates as __________.
monomers; it gets dimerized during transcytosis
Antigens lacking ___________ cannot be presented on MHC.
peptide exterior (that is, if they only have lipopolysaccharide such as Gram-negative bacteria, then APCs cannot present that in MHC)
What two receptor interactions are needed for T-cell activation?
MHC-II + antigen – CD4
CD80/86 (aka B7) – CD28
What two receptor interactions are needed for B-cell activation?
MHC-II + antigen –CD4
CD40 –CD40L
Five lab values with increase in response to acute inflammation and two will decrease. List them.
Increase:
- CRP
- Fibrinogen
- Ferritin
- Hepcidin
- Serum amyloid A
Decrease:
- Albumin
- Transferrin
Which complement cytokines can cause anaphylaxis?
C3a, C4a, and C5a
AAA can cause anaphylaxis.
What proteins form the membrane attack complex?
C5b –C9b
Which complement protein attracts neutrophils?
C5b
What is the alternative complement pathway?
C3 can spontaneously lyse on bacterial surfaces (that is, without mannose-binding lectin or C1)
Trace the classical complement pathway.
Antigen-antibody complexes activate C1.
C1 cleaves C2 and C4.
C4b2b (aka C3 convertase) cleaves C3.
C4b2b3b (aka C5 convertase) cleaves C5, activating the MAC.
How is the alternative pathway different?
C3bBb acts as C3 convertase, and C3bBb3b –yes, two 3bs –acts as C5 convertase.
ACE inhibitors are contraindicated in those with what complement disorder?
C1 esterase deficiency (characterized by angioedema of the face)
GPI anchors what receptor?
Decay-accelerating factor, also called CD55
Again, what is the “Hot T Bone stEAK” mnemonic?
IL-1: fever IL-2: T cell proliferation IL-3: bone marrow stimulant IL-4: igE production IL-5: igA production IL-6: aKute phase proteins (stimulating CRP)
