Immunology Chapter 1

Innate

Adaptive

Types of immune defenses

Immunity

State of protection

Specific for disease

Vaccines

Kick in adaptive defenses to get to immunity

Skips innate defenses

Antibiotics kill many commensal bacteria —> Pathogenic bacteria take up the space the normal flora previously occupied —> Produce toxins —> Mucosal injury —> RBCs & WBCs leak into the gut between the injured epithelial cells

How can long term antibiotic use lead to further infections (primarily in the gut)

Opportunistic Pathogen

Pathogen that can become harnful when new conditions arise

ie, c.diff, H. pylori

Bacteria

Virus

Parasites

Fungi

Types of pathogens

Protozoans - Eukaryotic

Helminthes - Worms, multicellular

Types of parasites

Innate Defenses

Immediate barriers & response (ie, skin, mucosal surfaces)

Skin

Physical barrier

Sebum

Creates an acidic environment on the skin’s surface

Mucous

Traps pathogens

Mostly in the upper respiratory tract

Cilia

Propels pathogens up and out of the body

Mostly in the upper respiratory tract

Lysozyme

Chemical compound that breaks down bacterial cell walls

1. Recognition - Cells (neutrophils)/Soluble components (complement) recognize something foreign

2. Response - Depends on what recognized the pathogen; Neutralize, kill, inflammation, etc

Innate Immune Response Stages

Inflammation

The innate immune response causes [?] at site of infection

Redness (erythema) & Heat (due to vasodilation)

Swelling (edema) (due to increased vascular permeability)

Pain (due to kinins)

S&S of Inflammation

1. Pathogen cell surface induces cleavage & activation of complement

2. One complement fragment (C3b) binds to pathogen; Other (C3a) attracts an effector Cell

3. Complement receptor on the effector cell binds to C3b on the pathogen

4. Effector cell engulfs the pathogen, kills it, & breaks it down

General: Pathogen-Recognition by effector cell using complement

Cytokines

Hormones of the immune system

Soluble proteins that interact with other cells to trigger the innate immune response

1. Surface wound introduces pathogen —> Activates effector cells in the area to secrete cytokines

2. Vasodilation & increased vascular permeability allows fluid, protein, & inflammatory cells to leave the blood and enter the injured tissue

3. Infected tissue becomes inflamed —> Redness, heat, pain, swelling

Inflammation pathway

Adaptive immune response

The [?] adds to an ongoing innate immune response

Adaptive Immune Response

Specific

Adaptable

Memory

1. Recognition by T or B cells

2. Response

Adaptive Immune Response stages

Rapid (within hours)

Fixed

Limited number of specificities

Constant

Characteristics of the recognition mechanisms of innate immunity

Slow (days-weeks)

Variable

Numerous highly selective specificities

Improves during response

Characteristics of recognition mechanism of adaptive immunity

1. Progenitor cells give rise to a large number of lymphocytes with different specificities DURING DEVELOPMENT

2. DURING INFECTION, lymphocytes with receptors that recognize the pathogen are activated

3. Proliferation of pathogen-activated lymphocytes (clonal selection) give effector cells that terminate the infection & produce memory cells to remember the infection

Stages of B/T Cell Response

Effector Cells

Memory Cells

Cell types made through clonal selection when certain lymphocytes proliferate and differentiate

Clonal Selection

Proliferation & differentiation of pathogen-specific lymphocytes —> Stimulated by the antigen

Creates Effector Cells & Memory Cells

Memory Cells

Goal of vaccines

Hematopoietic stem cells

Immune system cells w/ different functions all derive from [?]

Common lymphoid precursor

Common myeloid precursor

Hematopoietic stem cell creates…

Lymphoid lineage

B Cells, T Cells, and Natural Killer cells all come from the [?]

B-Cell

NK/T-Cell Precursor

Common lymphoid precursor creates…

T Cell

NK cell

NK/T Cell precursor creates…

Granulocyte-macrophage progenitor

Megakaryocyte/erthyroid progenitor

Common myeloid precursor creates…

Myeloid & Erythroid

The Common Myeloid Precursor creates the [?] & [?] cell lineages

Macrophage & Dendritic cell precursor

Neutrophil

Eosinophil

Basophil

An unknown precursor

Granulocyte-macrophage progenitor creates…

Mast Cell

The granulocyte-macrophage progenitor creates an unknown precursor which then creates …

Monocyte

Dendritic Cell

Macrophage & dendritic cell precursor creates…

Macrophage

Dendritic Cell (maybe)

Monocytes create…

Megakaryocyte

Erthyroblast

Megakaryocyte/erythroid progenitor creates…

Platelets

Megakaryocytes create…

Erythrocyte (RBC)

Erythroblasts create…

Neutrophils

Most abundant WBC

1st Responders

Short-lived - Last ~3 days

Kill Pathogens

Produce cytokines to start an inflammatory response

2 Major functons of the Neutrophil

Eosinophils

Fight parasites

(particularly helminthes

Mast Cells & Basophils

Primarily responsible for allergies

Dendritic Cells

Wander around looking for pathogens

Good at starting adaptive immune response

Phagocytosis = primary function

Monocytes & Macrophage

Killing pathogens through phagocytosis

Produce cytokines

Wander around blood stream (monocytes) & tissues (macrophages) looking for pathogens to kill

Macrophage

Monocyte that has entered the tissue

Natural Killer Cell

Type of lymphocyte

Larger than T & B Cells

Natural ability to kill tumor cells & fight viruses

Fighting viral infections

Tumor surveillance

Primary functions of natural killer cells

T & B Cells

Adaptive cells

Go through formal selection process (Clonal selection)

Bone marrow

Large reserves of neutrophils are stored in the [?] & are released when needed

Macrophages

As neutrophils die in the tissue after killing bacteria, they are then engulfed and degraded by [?]

Dead neutrophils

Pus is composed primarily of [?]

Binding of bacteria to phagocytic receptors on macrophages

What induces the engulfment & degradation of bacteria

Phagosome

Membrane-bound sac that forms around foreign pathogens during phagocytosis

Phagolysosome

Cytoplasmic body formed by the fusion of a phagosome and lysosome during phagocytosis in order to destroy engulfed pathogens

Synthesis & release of cytokines & initiation of inflammatory response

The binding of components of bacteria to signaling receptors on macrophages induces what?

Antibody

Structures on the surface of B Cells

Bind to pathogens & cause them to be inactivated or destroyed

Antigen-binding site

Variable regions

Constant regions

Transmembrane region

Top to bottom: Structures on the surface of B (antibodies) and T cells (T-Cell Receptor)

Antigen

Part of pathogen

Triggers immune response when binging to antibody

Effector cells - Plasma cells

Memory cells

Clonal Selection: B Cell + Antigen =

Effector cells - Cytotoxic T Lymphocytes (CTL) & helper cells

Memory cells

Clonal Selection: T Cell + Antigen =

Cytotoxic T Lymphocyte

Produced after T cells discover an antigen

Killer cells

Plasma Cells

Produced when B cells encounter antigens

Make antibodies

1. Toxin attaches to cell w/ receptors for toxin

2. Neutralization - Antibodies surround toxins

3. Antibodies w/ toxins gather near surface of phagocyte, leading to ingestion & destruction of toxins

Antibody response to bacterial toxins

1. Macrophage or dendritic cell encounter bacteria

2. Opsonization

   1. Antibodies surround the bacteria & bring it closer to macrophage surface

   2. Antibodies gather around bacteria and complement binds to bacteria

3. Ingestion & Destruction of bacteria

   1. Phagocyte surrounds bacteria w/ antibodies

   2. Complement binds to receptors on phagocyte, anchoring the bacteria for phagocytosis

Antibody response to full bacteria in extracellular space

Thymus

Primary lymphoid organ

Where T cells develop & mature

Bone Marrow

Primary lymphoid organ

Where B Cells develop & mature

Spleen

Peyer’s patches (in small intestine)

Adenoids

Tonsils

Lymph nodes

Where clonal selection happens

Secondary lymphoid organs

Clonal selection

Secondary lymphoid organs are determined as where [?] happens

Spleen

Where lymphocytes in the blood are circulated

Left Subclavian vein

Where lymph drains into to return to the heart

Lymphatic Capillaries

Structure where lymphocytes enter the tissue space

Afferent lymphatic vessel

Where lymphocytes exit the lymph node

Efferent lymphatic vessel

Where lymphocytes enter the lymph node

Lymphatic Capillaries

Lymphatic vessels

Lymphoid follicle

Afferent lymphatic vessel

Secondary follicle

Germinal center

Efferent lymphatic vessel

Lymph node structures

is not an antigen

The lymphocyte leaves the lymph node when there [is/is not] an antigen

Valves

There are [?] along the afferent and efferent lymphatic vessels to prevent backflow

Secondary lymphoid tissues

Adaptive immunity is initiated in [?]

Dendritic cells carrying pathogens

The adaptive immune response is activated by [?] being drained into the lymph node

Paracortex

In the lymph node, the T-cell area is called the [?]

Cortex

In the lymph node, the B-cell area is called the [?]

Germinal Center

Active center of B cell activity in the lymph node

Medullary Sinus

In the lymph node, Plasma cells mostly reside in the [?]

Lymphoid follicle/cortex (B-cell area)

Medullary sinus

Paracortex/T-cell area

Germinal center

Marginal Sinus

Afferent & Efferent lymphatic vessels

Artery & Vein

Structures of the Lymph node

Tissue

Lymph nodes drain [?] of pathogens

Blood

Spleen drains [?] of pathogens

Get rid of old RBCs

Start immune response

Functions of the Spleen

White pulp

[?] of the spleen initiates immune responses

Red pulp

[?] of the spleen is where RBCs are destroyed

B-Cell corona - young

Germinal center - mature

Area where B-cells are in the white pulp of the spleen

Periarteriolar lymphoid sheath

Area where T-cells are in the white pulp of the spleen

Perifollicular zone

Marginal zone

B-Cell Corona

Germinal Center

Central arteriole

Periarteriolar lymphoid sheath

Structure of the white pulp of spleen

M cell

Dendritic cells

In the gut, antigens get into lymphoid tissue through the [?] in the epithelium surrounding the gut lumen, activating [?]

Efferent lymphatic vessels to a larger lymph nodes

Gut-associated lymphoid tissues drain through the [?]

Opsonization

Coating of antibodies on pathogen facilitate phagocytosis by attaching to receptors on phagocytes

Neutralization

Antibodies bind tightly to a site on a pathogen to inhibit its growth, replication, or interaction with human cells

Tonsils

Adenoids

Appendix

Peyer’s patches

Gut-Associated Lymphoid Tissues