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Immunology Flashcards

1
Q

cell type kills viruses?

A

CD8 cytotoxic T cells

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2
Q

What’s the purpose of opsonization? Most important opsonins?

A

enhance phagocytosis of foreign cells (eg bacteria)

- Most important: IgG, C3b. Also mannose-binding lectin and CRP

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3
Q

What does C3a do?

A

recruit phagocytic cells and induce inflammation

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4
Q

What does C3b do?

A

Acts as an opsonin (coat proteins for phagocytosis)

Form C5 convertase –> membrane attack complex (MAC)

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5
Q

What does C5a do?

A
  1. enhance phagocytosis by macrophages by binding to receptors on phagocytes and stimulating them directly. Does NOT coat the foreign cell.
  2. Chemotactic agent for neutrophils and monocytes
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6
Q

Process of desensitization for allergies is thought to move the ___ type cytokine response to the allergen into the ___ type cytokine response to that allergen.

A

Th2
Th1

IgE levels are reduced and IgG levels are increased

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7
Q

LN anatomy: outer cortex contains what?

A

primary and secondary lymphoid follicles (B-cell rich)
Has CD4+ T cells in the interfollicular regions too.
This region is diminished in agammaglobulinemia (B cell def)

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8
Q

LN anatomy: paracortical zone contains what?

A

T lymphocytes and dendritic cells

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9
Q

LN anatomy: germinal center

A

B cells

This region will not form in Bruton X-linked agammaglobulinemia (B cell def)

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10
Q

Auer rods are seen in what?

A

AML

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11
Q

Severe hypoplasia of marrow erythroid elements in the setting of normal granulopoiesis and thrombopoiesis. What is it assoc with?

A

Pure red cell aplasia

Assoc with thymoma, lymphocytic leukemia, parvovirus B19

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12
Q

The green discoloration of pus or sputum seen during common bacterial infections is due to the presence of what?

A

Myeloperoxidase - blue-green heme-based enzyme that is released from neutrophil azurophilic granules and forms hypochlorous acid (bleach)

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13
Q

What is the only cytokine with anti-inflammatory properties?

A

IL-10

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14
Q

What is the surface marker of the monocyte-macrophage cell lineage and recognizes LPS on GN bacteria?

A

CD14

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15
Q

Painful abdomen, wine colored urine, polyneuropathy, behavioral change, precipitated by drugs (eg CYP450 inducers). Dx? Deficiency? Excess?

A

Acute intermittent porphyria
Def: porphobilinogen deaminase
Excess: d-ALA, porphobilinogen

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16
Q

Blistering cutaneous photosensitivity with tea colored urine Dx? Deficiency? Excess?

A

Porphyria cutanea tarda
Def: uroporphyinogen decarboxylase
Excess: uroporphyrin (causes tea colored urine)

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17
Q

Lead poisoning affects what enzymes? Excess?

A

Def: ferrochelatase; ALA dehydratase
Excess: protoporphyrin, d-ALA

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18
Q

Bee sting causes edema (extravascular accumulation of fluid) how?

A

gap formation between endothelial cells

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19
Q

T cell differentiation: T cells expressing TCRs capable of binding self-MHC on cortical epithelial cells survive. Where is this located?

A

Positive selection - thymic cortex

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20
Q

T cell differentiation: T cells expressing TCRs with high affinity for self-antigens undergo apoptosis. Where is this located?

A

Negative selection - thymic medulla

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21
Q

Protein complex that activates immune response genes by controlling transcription of DNA, cytokine production and cell survival. How is it activated?

A

NF-kB
IkB is phosphorylated–> ubiquitinated/degraded –> NF-kB is released and able to enter the nucleus
(YopP in Yersinia pestis prevents ubiquitination/degradation) so no immune response

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22
Q

patient with SCID who requires transfusion should get what type of RBC?

A

irradiated - destroys the DNA in the white cells
Also done to prevent graft versus host disease, which may happen if the blood donor and recipient are closely related or for other immunocompromized patients.

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23
Q

Plasmodium (malaria) infect erythryocytes which are the only cells that do not express ______, which require ____ cells to clear the infection in the erythrocytic stage?

A
  1. MHC class I antigens

2. NK cells

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24
Q

Deficiency in this causes defects in opsonization and removal of immune complexes.

A

C3
inc susceptibility to extracellular bacteria that use complement for clearance. eg S pneumo, H influenza, N meningitidis

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25
Q

Immature neutrophils have dec expression of Fc receptor, which is shown with what cell marker?

A

CD16

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26
Q

Inc eosinophilia is seen with what conditions and has elevated levels of what?

A

allergic reaction
parasite infection
hodgkins lymphoma
IL-5 increased

27
Q

Basophilia is assoc with what condition?

A

CML

28
Q

Viral infections traditionally increase CD8 cells. What is one bacteria that also increases these cells?

A

Bordatella pertusis

29
Q

4 key mediators that attract neutrophils

A

LTB4
C5a
IL8
Bacterial products

30
Q

Anaphylaxis is due to widespread mast cell and basophil degranulation which releases histamine and what other pre-formed inflam mediator?

A

Tryptase - used as a marker for mast cell activation

31
Q

The immune system reacts to tissue parasites such as Ascaris by coating them with what?

A

IgE antibodies, triggering eosinophil-mediated cytoxicity and release of vasoactive substances from mast cells and basophils (Type 1 HSR)

32
Q

Langhans giant cells are characteristic in granulomatous conditions - have multiple nuclei peripherally organized in a horseshoe shape. Macrophages that form these are activated by what?

A

CD4 Th1 lymphocytes

33
Q

What are the 2 most important factors for osteoclastic differentiation

A
  1. macrophage colony-stimulating factor (M-CSF)

2. receptor for activated nuclear factor kappa-B ligand (RANK-L)

34
Q

Patient with pain and deformity of long bones with hearing loss and osteoclasts with up to 100 nuclei

A

Paget’s disease of bone

Normal osteoclasts have 2-5 nuclei.

35
Q

What cells and cell products contribute to formation of granulomas in sarcoidosis?

A

Th1, Il-2, IFNy, TNF-a !!!

36
Q

Eosinophils are important for host defense during parasite infections. How do they destroy the parasite?

A

Antibody-dependent cell-mediated cytotoxicity with enzymes from their cytoplasmic granules. They also regulate type I HSR (but not for parasites)

37
Q

Viral infections produce IFN a and b which suppress viral infection how?

A

suppresses viral replication by halting protein synthesis and promoting apoptosis of infected cells.

38
Q

What cell surface markers are used to ID natural killer (NK) cells?

A

CD16 and CD56.
CD16 is the Fc receptor that helps Nk cells mediate ab-dependent cell-mediated cytotoxicity.
Note: treatment of IgG with PAPAIN yields 2 Fab and destroys the Fc portion, preventing capping, precipitation, and agglutination.
Present in ATHYMIC patients; activated by IFN-y and IL-12
Recognize and kill cells with dec MHC class I (eg virus-infected cells and tumor cells)

39
Q

Why are patients with multiple myeloma more prone to frequent, severe infections?

A

Infections occur because neoplastic plasma cells do not function well

40
Q

Activation of which cells are responsible for the response to Toxic Shock Syndrome?

A

Macrophages and T lymphocytes
Superantigns interact with MHC on APCs and the variable region of T lymphocyte receptors –> T cell activation –> IL-2 release from T cells and IL-1 and TNF release from macrophages

41
Q

Sputum eosinophils, normal CXR and reduced FEV1/FVC suggest what?

A

Asthma (eg from exercise, dust mites, dander)

42
Q

Differentiation the 2 types of pneumonia vaccines

A

23 - polysaccharide vaccine (polysacc cannot be presented to T cells, so induces T cell INDEPENDENT B cell response that is less effective)
13 - conjugate vaccine (capsular polysacc covalently attached to recombinant, inactivated diphtheria to induce Tcell DEPENDENT B cell response)

43
Q

IFN-Y release assays test for latent Tb by measuring amount of IFN-y released by ____ when exposed to ags unique to M tb

A

T lymphocytes

44
Q

Skin biopsy of thigh of child demonstrating vascular lesions with IgA and C3 deposition is likely due to what?

A

HSP

will see skin rash and abdominal pain

45
Q

Initiation of apoptosis via extrinsic pathway involves what?

A

Engagement of death receptors (TNF receptor family) on the cell surface. TNFR1 and Fas (CD95) are best known.
Note: Fas mutations prevent apoptosis of autoreactive T lymphocytes –> inc risk of autoimmune disease like SLE
Stim caspases downstream

46
Q

Initiation of apoptosis via intrinsic pathway involves what?

A

Mitochondrial path - mito become more permeable and pro-apoptotic substances (cyt c) are released into the cytoplasm

47
Q

How does calcineurin affect transplants?

A

Calcineurin activates IL-2 –> T cell growth and diff

Immunosuppressants inhibit calcineurin activation (cyclosporine, tacrolimus)

48
Q

Function of IL-2

A

stim growth of CD4+ and CD8+ T cells and B cells.

Also activates NK cells and monocytes (has an anti-cancer effect on metastatic melanoma and RCC)

49
Q

What is an effective add-on therapy for patients with severe allergic asthma that reduces dependency on both oral and inhaled steroids?

A

Omalizumab - anti-IgE antibodies

Many asthmatics have allergies as a trigger due to high IgE response

50
Q

Patient who received the inactivated flu vaccine is exposed to the flu. The patient’s prior exposure to the vaccine will result in what?

A

Inhibition of viral entry into the cells.

Inhibit binding of hemagglutinin to sialylated receptors on the host cell membrane.

51
Q

Most important mediator of sepsis (hypotension, tachy, tachypnea, inc temp)

A

TNF-a

Note: IL-1 and IL-6 also induce the systemic inflam response

52
Q

What causes graft vs host disease?

A

Graft T cell sensitization against host MHC antigens

Note: acute and chronic graft rejections occur following host T and B cell sensitization against graft MHC antigens

53
Q

What causes elevated ESR?

A

Cytokines: IL-1, IL-6, TNF-a mediate systemic inflam response –> secretion of fibrinogen –> inc ESR

54
Q

What are important chemotactic agents?

A

Leukotriene B4 - stim neutrophil migration
5-HETE (leukotriene precursor)
C5a, IL-8

55
Q

C1 inhibitor deficiency causes inc cleavage of C2 and C4 –> inappropriate activation of the complement cascade. What else does it block?

A

Blocks kallikrein-induced conversion of kininogen to bradykinin (potent vasodilator assoc with angioedema)
Causes elevated bradykinin –> bradykinin-assoc angioedema (facial swelling w/o urticaria), laryngeal edema, GI sx.
Tx - C1INH concentrate or kallikrein inhibitor

56
Q

Differentiate MHC class I and class II structure

A

Class I - heavy chain + B2 microglobulin

Class II - a and b polypeptide chains

57
Q

What type of cancer produces the highest antibody titer and why?

A

Cervical cancer - HPV
Most cancers have antigens that are “SELF” Proteins that are normally made by the body and thus will be poorly immunologic. Only HPV/E6 in an example of a Foreign Antigen that will induce a vigorous immune response.

58
Q

Patient with superficially invasive melanoma with features of regression. What explains the lesion’s regression?

A

Mechanism of regression: T-lymphocyte-mediated cytotoxicity (cell-med immunity)
immune response that does not involve antibodies or complement but rather involves the activation of macrophages, natural killer cells (NK), antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.

59
Q

PPD skin test to determine if infected with M tb. If positive, analysis of the lesion is most likely to show predominance of what cell type?

A

Macrophages.
CD4+ T cells activate Th1 cells then activation of macrophages
IFN-gamma macrophages cause inflammation

60
Q

Treatment of febrile neutropenia?

A

G-CSF (filgastrim) - supports the absolute neutrophil count

61
Q

What causes induration at the site of a bee sting a few hours after it occurs?

A

Influx of macrophages producing IL-1, IL-6 and TNF-a

62
Q

Determine what kidney allograft is most compatible with the patient:
In this test, “stimulator” lymphocytes from a potential donor are first killed by irradiation and then mixed with live “responder” lymphocytes from the recipient; the mixture is incubated in cell culture to permit DNA synthesis, which is measured by incorporation of tritiated thymidine.

A 
Want the lowest amount of cell stimulation
The greater the amount of DNA synthesis in the responder cells, the more foreign are the class II MHC proteins of the donor cells. A large amount of DNA synthesis indicates an unsatisfactory "match"; i.e., donor and recipient class II (HLA-D) MHC proteins are not similar, and the graft is likely to be rejected. The best donor is, therefore, the person whose cells stimulated the incorporation of the least amount of tritiated thymidine in the recipient cells.
63
Q

Inability to express B2-microglobulin results in what immune response defect?

A 
Cytotoxic T lymphocytes will be altered
B2 microglobulin is a component of MHC class I, which are present on all nucleated cells (except RBC)
64
Q

How does the effect of a monoclonal antibody (eg infliximab) wear off over time?

A

Most “biologics” are monoclonal antibodies. Infliximab (remicade) and adalimumab (humira) for example both block TNF-alpha and are both mouse antibodies (end in “mab” for mouse antibody). As such, the body can eventually form an immune-response to the foreign protein.

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