Coll 1 Additional Questions Flashcards by Julia Styczen

What are the primary organs of the immune system?

bone marrow
thymus

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What is the main function of primary immune system organs?

development and maturation process of lymphocytes

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What is the function of the bone marrow?

Origin of all blood cells;
B cell maturation.

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What is the function of the thymus?

T cell maturation (positive and negative selection to prevent autoimmunity).

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What are the secondary immune system organs?

lymph nodes
spleen
mucosa-associated lymphoid tissue (MALT)

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What is the main function of secondary lymphoid organs?

initiation of immune responses

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What is the function of lymph nodes?

Filter lymph, activate T and B cells.

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What is the function of the spleen?

Filters blood,
destroys old RBCs,
detects bloodborne pathogens.

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What is the function of MALT?

Mucosa-associated lymphoid tissue:
- found in gut (GALT), respiratory tract (BALT), etc.,
- defends mucosal surfaces.

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State examples of Th2 cells.

CD4+
T-helper cells

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What is the function of Th2 cells?

Promote humoral (antibody-mediated) immunity.

Activate B cells → class switching to IgE.
Secrete cytokines: IL-4, IL-5, IL-13 (important for allergies and parasite defense).
Support eosinophil activation (against helminths).

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Explain Th2 mechanism of action.

Recognize antigen on MHC II.
Secrete IL-4 → Induces B cells to produce IgE.
IL-5 → Activates eosinophils.
IL-13 → Enhances mucus secretion in the gut.

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What is the function of treg cells?

Treg cells (Regulatory T cells):
- Suppress immune responses,
- prevent autoimmunity.

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What do FoxP3+ Tregs secrete? Function?

IL-10, TGF-β → Inhibit excessive immune activation.

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State the importance of MHC I in T-cell activation. What do they act on?

on all nucleated cells
presents endogenous antigens (e.g., viral proteins) to CD8+ cytotoxic T cells.

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State the importance of MHC II in T-cell activation. What do they act on?

on APCs like macrophages, dendritic cells, B cells
presents exogenous antigens to CD4+ helper T cells

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What is the main function of MHC molecules?

crucial for T cell activation, ensuring specificity and immune memory

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What are cytokines?

Signaling molecules that regulate immunity.

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What are chemokines?

Signalling molecules that direct cell migration.

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What are the pro-inflammatory cytokines?

IL-1,
IL-6,
TNF-α

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What are the anti-inflammatory cytokines?

IL-10,
TGF-β

What are the Th1 cytokines? What are their functions?

IFN-γ (activates macrophages).

What are the Th2 cytokines? What are their functions?

IL-4, IL-5, IL-13 (promote B cell response).

State examples of chemokines and their functions.

CCL2- recruits monocytes.
CXCL8 (IL-8)- attracts neutrophils.
C5a- attracts neutrophils

Explain the processing and presentation of antigens on MHC I molecules.

Endogenous (Internal) Antigens (e.g., viral proteins): processed in the **proteasome** → transported to **ER** → presented on **MHC I** → recognized by **CD8+** T cells.

Explain the processing and presentation of antigens on MHC II molecules

Exogenous (External) Antigens (e.g., bacteria, fungi): Engulfed by **APC**s → processed in **endosomes** → presented on **MHC II** → recognized by **CD4+** T cells.

Explain the concept of the superantigen.

- Superantigens (e.g., TSST-1 in Staphylococcus aureus) bypass normal antigen processing by binding directly to **MHC II** and **TCR**. - Causes massive T cell activation, cytokine storm, and toxic shock.

What are the types of non-specific immunity responses?

**Barrier defenses**: Skin, mucous membranes, stomach acid. **Cellular defenses**: Macrophages, neutrophils, NK cells. **Soluble mediators**: Complement system, cytokines, acute-phase proteins.

Explain the formation of acute-phase proteins.

- produced in the liver - in response to IL-1, IL-6, TNF-α.

State examples of acute-phase proteins and their functions.

**CRP** (C-reactive protein)- opsonizes bacteria. **Mannose-binding lectin** (MBL)- activates complement. **Fibrinogen**- involved in clotting.

What is septic shock?

a systematic response to a bacterial infection

Explain what happens during septic shock.

1) Massive cytokine release: - TNF-α, - IL-1, - IL-6) 2) Vasodilation 3) Hypotension. DIC (Disseminated Intravascular Coagulation): - Clotting dysfunction leads to organ failure.

What is the cause of the toxic shock syndrome?

superantigens

What is the role of macrophages in toxic shock syndrome?

secrete TNF-α and IL-1, causing shock, fever, organ failure.

What is chronic inflammation?

persistent immune activation.

What are the products of macrophages in chronic inflammation?

TNF-α, IL-6 → Inflammation. IL-10, TGF-β → Fibrosis. Reactive oxygen species (ROS), NO → Tissue damage.

What is the role of M1 macrophages?

(**pro-inflammatory**): - secrete **TNF-α**, **IL-6**, **IL-1**, **IFN-γ ** → **Kill pathogens**.

What is the role of M2 macrophages?

M2 macrophages (**anti-inflammatory**): - Secrete **IL-10**, **TGF-β** - → **Tissue repair**.

Explain the stages of neutrophil migration.

**Rolling** (Selectins slow down neutrophils). **Adhesion** (Integrins bind to ICAM). **Diapedesis** (Neutrophils squeeze through vessel walls). **Migration** (Follow chemokine gradient, e.g., CXCL8).

What is opsonization?

the coating of pathogens for phagocytosis

What are the key opsonins?

**IgG** (Fc receptor-mediated recognition). **C3b** (Complement-mediated recognition).

What is agglutenation?

particulate antigens clump when mixed with antibodies (e.g., blood typing).

What is precipitation?

soluble antigens form visible complexes with antibodies.

What reaction does blood typing involve?

blood typing (antigen-antibody reactions)

Explain blood typing.

Anti-A/B antibodies react with corresponding antigens, causing **agglutination**.

What are the blood types of cats?

Blood types A, B, AB. - No universal donor; - mismatched transfusions can cause fatal hemolysis.

What are the blood types in dogs?

DEA System (Dog Erythrocyte Antigens): - 1 (1.0, 1.1 (most antigenic), 1.2) - 2 - 3 - 4 (most frequent) - 5 - 6 - 7 - 8 Species specific: - Dal

What is the universal dog donor?

DEA 1.1-negative dogs

What are the available shortcuts for dog blood typing?

- limit the test to DEA 4 and DEA 1 - check compatibility bewteen the reciever and donor

Which blood transfusion is the safest (when blood groups are unknown)? Why?

first blood tranfusion, as antibodies are not produced fast enough to react with the antigens present on the erythrocytes