Chapter 1

what parts of the body form the first defense

physical barriers: skin, mucosal surfaces, cilia, mucosal enzymes

what chemical barriers does the skin produce

fatty acid and lactic acid

where is lysozyme produced

salivary glands, lacrimal glands

innate immunity order of events

barrier breeched → patterns recognized → signals released → cells recruited → threat contained

immunity

defense against foreign material and abnormal cells

adaptive immunity

includes humoral (antibody-mediated) and cell-mediated responses

how does innate immunity influence adaptive immunity

it influences whether adaptive immunity activates, what kind of response adaptive immunity develops, and where the immune cells go

what does innate immunity recognize

patterns shared by microbes or damaged cells

what does adaptive immunity recognize

specific antigens

how does memory compare in innate immunity and adaptive immunity

memory is stronger in adaptive immunity

main purpose of innate immunity

contain, kill, and signal

main purpose of adaptive immunity

more targeted response

neutrophils

the most abundant; rapid phagocyte common in acute inflammation

monocyte/macrophage

phagocyte + signaling

what are three examples of external defenses

physical, chemical, and biological barriers

What is the role of normal microbiota in defense?

They compete with pathogens and help maintain local defense.

What are three key characteristics of innate immunity?

It is rapid, broad, and already present before exposure.

are nk cells innate or adaptive

innate

13. Q: What is the major role of dendritic cells?

A: Capture antigen and activate naïve T cells, bridging innate and adaptive immunity.

What do mast cells and basophils primarily produce?

release histamine, which is involved in allergic rxns and vasodilation

What are eosinophils associated with?

Parasites and allergy.

What is the major function of NK cells?

Innate cytotoxicity—killing altered host cells.

role of b cells

antibody lineage

t cell

cellular coordination/killing

where do plasma cells come from and what do they secrete

come from naive b cells and secrete antibodies

where are macrophages found

tissue

where are monocytes found

blood

in innate immunity which cell does cytokines come from

macrophages

what are 3 APC cells

dendritic, macrophage, b cell

CD what does it stand for

cluster of differentiation

What is the main marker for T cells?

CD3.

What marker identifies helper T cells?

CD4; helps coordinate immune response

What marker identifies cytotoxic T cells?

CD8; kills infected cells

What markers identify B-cell lineage?

CD19 and CD20

What markers are associated with NK cells?

CD16 and CD56

What are the primary lymphoid organs?

Bone marrow and thymus.

What are the secondary lymphoid organs?

Lymph nodes, spleen, tonsils, adenoids, Peyer patches, and MALT.

What happens in the bone marrow?

T and B cells produced, but only B cells mature

What happens in the thymus?

T-cell maturation and selection.

purpose of secondary lymphoid tissue

sites where immune cells encounter material from tissues, blood, or mucosa.

what is A and B?

A = spleen

B = lymph nodes

What is the main job of lymph nodes?

Monitor/filter tissue fluid and lymph and provide a site for B-cell and T-cell antigen encounters.

what is the job of the cortex/follicles of the lymph node

B-cell area; germinal centers form during active responses.

what is the role of the paracortex of the lymph node

T-cell area; important for APC and T-cell interaction.

label parts of the lymph node

1. germinal center

2. paracortex (t cell area)

3. medulla

4. primary follicle

5. cortex (b cell area

6. capsule

Which lymphoid organ is associated with blood

spleen

Which lymphoid organ is associated with tissue fluid/lymph?

lymph nodes

Which lymphoid tissue is associated with mucosal surfaces?

MALT

purpose of white pulp in spleen

organizes lymphocytes

purpose of red pulp in spleen

filter blood cells and particles

example of MALT

peyers patch

_____ _____ starts the internal response.

pattern recognition

What is a PAMP?

A pathogen-associated molecular pattern—a common microbial structure.

What is a PRR?

A pattern recognition receptor on host cells that binds PAMPs or damage signals.

what is example of PRR

toll-like receptors

what happens when PAMP binds to PRR

triggers internal response leading to release of cytokines, chemokines, increased phagocytosis

cell surface TLR

detect microbial surface structures such as bacterial cell-wall components or flagellin.

endosomal TLR

detect microbial nucleic acids after uptake into vesicles.

What do cytokines do?

They are soluble messages that change cell behavior.

What do chemokines do?

Guide cell movement toward a site of infection or damage.

how does recognition turn on signaling

PRR activates → cytokines released → chemotaxis → vasodilation → leukocytes arrive

inflammation ____ the response.

localizes

how does swelling happen

increased permeability of blood vessel allows fluid to escape → edema

What are the four classic signs of inflammation?

Redness, heat, swelling, and pain. 5th could be loss of function

which 2 leukocytes respond in chemotaxis

neutrophil and macrophage

1st step of leukocyte recruitment

mediator release - macrophages and mast cells release chemokines which promote vasodilation and induce selectin expression on endothelial cells

2nd step of leukocyte recruitment

rolling - leukocytes bind to selectin and roll along the endothelium

3rd step of leukocyte recruitment

firm adhesion - chemokine-induced integrin on leukocytes attach to endothelial cell

4th step of leukocyte recruitment

diapedesis - integrins allow leukocytes to crawl between endothelial cells

5th step of leukocyte recruitment

chemotaxis - leukocytes have left the blood vessel and can now follow chemokine gradient to arrive at site of infection

acute phase reactants

blood proteins whose concentrations change during inflammation.

steps in acute-phase response

tissue injury/infection → cytokine signal → liver responds → serum protein changes

What is a positive acute-phase reactant?

A serum protein that increases during inflammation, injury, or infection.

What is a negative acute-phase reactant?

A serum protein that decreases during the acute-phase response.

What is CRP associated with?

C-reactive protein (CRP) Inflammation; it is an opsonin and can activate complement.

SAA

inflammatory acute-phase protein

compliment

opsonization, inflammation, and lysis support

AAT

protease inhibitor; protects tissue

What does haptoglobin do?

Binds free hemoglobin.

What does fibrinogen do?

 Contributes to clotting/healing and increased ESR tendency.

ceruloplasmin

copper transport; oxidative protection

steps of phagocytosis

attachment → engulf → phagosome → lysosomal fusion → phagolysosome → killing → excretion

What is an opsonin?

A molecule that coats a target and improves phagocyte attachment.

What are three important opsonins

antibodies, C3B, CRP (c-reactive protein)

what are 2 enzymes used in phagolysosome

NADPH oxidase and myeloperoxidase

NADPH oxidase

generates RO species

myeloperoxidase

uses hydrogen peroxide and chloride to form hypochlorite (bleach).

Chronic granulomatous disease

NADPH oxidase deficiency impairs oxidative killing. the phagocyte can ingest microbe but cant kill it

symptom of Chronic granulomatous disease

reacurrent infections and persistent inflammation

What does “missing self” mean for NK cells?

An altered or infected cell has missing or abnormal MHC class I, removing the normal inhibitory signal and allowing NK-cell activation

What molecules do NK cells use to kill target cells?

Perforin and granzymes.

What is ADCC?

Antibody-dependent cellular cytotoxicity.

steps of ADCC

1. antibody coats target cell

2. NK cell uses CD16 to bind to Fc region of antibody

3. NK cell releases toxic molecules and target cell dies by apoptosis