- alpha and beta - function: induce viral resistance - produced by almost any cell in the body - can suppress T cell response and memory T cells in HIV - may interfere with bactericidal mechanisms

- gamma only - secreted ONLY by NK cells and T lymphs - Function: signals the immune system to respond to cancer or infectious agents

Immuno I Flashcards by Melissa Aswad

Antigen

anything that causes an immune response; “pathogens”

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Antibody

immunoglobulin; protein molecule created by our immune system to target an antigen for destruction
-IgG, IgA, IgM, IgE, IgD

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Cytokine

cell to cell communication proteins that control cell development, differentiation, and movement to a specific part of the body

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What produces cytokines?

WBCs

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Interleukins

13 cytokines that help regulate immune responses, inflammatory reactions, and hematopoiesis

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IL-1 & IL-6

responsible for fever (pyritic response)

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IL-6 type of response

acute phase response

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Tumor necrosis factor (TNF)

activates neutrophils, mediates septic shock, causes tumor necrosis

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Chemokines

type of cytokine released by injured cells that initiate an immune response and warn neighboring cells

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Interferons (IFN)

block virus replication; can be used to treat diseases

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Three subtypes of IFN

IFN-a, IFN-beta, IFN-gamma

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Which IFN is the strongest?

IFN-gamma; produced by T cells; activates macrophages, NK cells, and neutros

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Type I IFN

alpha and beta
function: induce viral resistance
produced by almost any cell in the body
can suppress T cell response and memory T cells in HIV
may interfere with bactericidal mechanisms

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Type II IFN

gamma only
secreted ONLY by NK cells and T lymphs
Function: signals the immune system to respond to cancer or infectious agents

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Two branches of the immune system:

Innate (fast)

Adaptive (slow)

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Locations of hematopoiesis

Embryo/fetus: liver, spleen, thymus

Birth to adult: bone marrow

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Characteristics of innate immunity

fast
immediate
non-specific
response does NOT increase with repeat exposure

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Components of innate immunity

physical barriers (skin, mucous membranes)
Granulocytes (neutros, basos, eos, mast cells)
Monocytes and macrophages
Dendritic cells
NK cells
Complement cascade

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1st step of innate immune system: Physical barriers (components)

Skin (acidic sweat, fatty acids and enzymes)
Mucous membranes (contain lysozymes against gram-pos bacteria, gastric secretions, acidic pH)
Commensal bacterial

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2nd step of innate immune system

inflammatory response

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Physiologic results of the inflammatory response

Vasodilation and leaky capillaries
Decreased clotting
Result in increased blood flow to the area

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Steps of the inflammatory response (4)

1) Damaged tissues release histamine (increases blood flow)
2) Histamines cause capillaries to leak (releases phagocytes and clotting factors into damaged area)
3) Phagocytes engulf bacteria, dead cells, and cellular debris
4) Platelets move out of the capillary to seal wounded area

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Adhesion molecules

membrane proteins that connect cells to other cells or the ECM; play a role in recruitment of neutrophils to wound

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Results of chronic inflammation

Chronic cytokine release and WBC infiltration –> release of lysozyme and free radicals –> tissue damage

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Basophils

- least common - Allergic and helminth responses - Release histamine and heparin

Eosinophils

- 1-6% of WBCs - Circulate in bloodstream and present in organs (esp. GI and respiratory tract) - Release H2O2, oxygen radicals, and leukotrines (lipid-signaling molecules that cause smooth muscle in airways to contract) - Active in allergic reactions and asthma - Stimulate T cells - APCs - Weakly phagocytic

Neutrophils

- Most abundant - Fast first responders - Esp. strong against bacteria and fungi - Recruited by cytokines and release other cytokines to recruit macrophages and monocytes - STRONGLY PHAGOCYTIC - Produce NETs

Mast cells

- Release histamine and heparin - Leave BM as immature cells and mature in tissues - Present in "boundary" tissues b/w "inside" and "outside" - MASSIVE RELEASE of histamine --> anaphylaxis

Monocytes

- agranular - Half stored in spleen - Half migrate to tissues and differentiate into DCs and macros

Functions of monos, macros, and dendros

- Phagocytosis - APCs - Cytokine production

Dendritic cells (DCs)

Strongest APC that activates helper T (T4) cells | -Capture antigens and migrate to LNs to present the antigen to T and B cells

Langerhands cells

specialized DCs in skin

Macrophages

- large phagocytes - release TNF and ILs - APCs - Present in skin, lungs, GI tract, etc.

Three stages of macrophage readiness

1) Resting (scavenging cellular debris) 2) Primed (more active engulfing of bacteria and acting as APCs 3) Hyper-activated (inflammatory cytokines cause them to enlarge and start rapidly destroying bad cells)

After digesting a pathogen, a macrophage will present the antigen to a _______ cell via displaying it attached to a MHC class ___ molecule.

T helper; II

Kupffer cells

specialized macros within the liver; chronic activation can cause liver cell damage or cancer

NK cells

- cytotoxic lymphocytes that kill all the time, but esp. well when activated by cytokines - esp. active against viruses and cancerous cells - granules that contain destructive enzymes

What do NK cells release to kill their targets?

perforins, proteases

What methods do NK cells use to kill their targets?

cell membrane lysis; apoptosis

What cells serve to contain viral infections while the adaptive immune response is generating antigen-specific cytotoxic T cells?

NK cells

What cell surface molecules help the immune system determine if a protein is "self" or "non self"?

MHC or HLA proteins

What is the function of MHC proteins?

Bind antigen to cell surface and display for recognition by T cells

What are produced b the liver in response to inflammation-induced release of IL-1, IL-6, and TNF by macros and T cells?

acute phase proteins

List 3 acute phase proteins:

1) CRP 2) Mannose-binding lectin 3) LPS-binding protein

What enhances the ability of phagocytic cells to destroy pathogens?

complement system

What are the 3 complement activation pathways?

1) Classical 2) Alternative 3) Lectin

What is complement activated by?

antigens

Where are complement proteins made?

liver

What is the most abundant complement protein in humans?

What are the components of the membrane attack complex (MAC)?

C5b, C6, C7, C8, C9

What component of the adaptive immune system directly blocks binding of the invaders to cells?

antibodies

What component of the adaptive immune system inactivates viruses and neutralizes toxins?

antibodies

What component of the adaptive immune system "marks" pathogens for destruction via opsonization?

antibodies

``` Structure of antibodies: __ light chain(s) __ heavy chain(s) ____-binding site ____ region ____ region ```

``` 2 light 2 heavy antigen-binding Fab (variable) Fc (constant) ```

Is the Fab region of an antibody variable (antigen-specific) or constant (class effect)?

variable/antigen-specific

Is the Fc region of an antibody variable (antigen-specific) or constant (class effect)?

constant

IgM

- biggest - 1st produced - 10 day half-life - recent exposure to antigen

IgG

- 4 classes - Only class that crosses the placenta - Longest half-life (23 days) - Late in primary response, biggest in secondary response

What antibody class is used for passive immunization for rabies and hepatitis?

IgG

What class of AB helps NK cells find and opsonize their targets?

IgG

Where is IgA primarily found?

external secretions

What antibody is found in breast milk and helps protect the infant?

IgA

What antibody is found primarily in the respiratory and GI tracts?

IgA

IgE

- low amts in serum - Short half-life (2 days) - Increased in atopic indiv. and parasites

What antibody class binds to mast cells and basophils?

IgE

What antibody has granules containing histamine, leukotrines, and heparin?

IgE

What antibody is present on the surface of naive B cells?

IgD

What are the characteristics of the adaptive immune system?

- cell-mediated/humoral - slow (days to develop) - specific response - develops memory - subsequent exposures have a more rapid and intense response

Components of the adaptive immune system?

T and B cells, antibodies, complement, APCs

What are the primary lymphoid organs?

Thymus (children) and BM (adults)

What are the secondary lymphoid organs?

Spleen, LNs, tonsils, adenoids, appendix

Where are antigens present to mature naive B and T cells to initiate adaptive immune response?

secondary lymphoid organs

What cells eliminate extracellular pathogens?

B cells

What cells produce antibodies?

B cells

What are the clones of B cells that produce antibodies?

plasma cells

What cells destroy intracellular pathogens?

T cells

What type of T cell specializes in killing virally-infected cells?

CD8/cytotoxic/killer

What type of T cell raises the alarm via cytokines but doesn't directly kill pathogens?

CD4/helper

What cells signal B cells to begin secreting antibodies?

Helper T/CD4 cells