mcmp 422 tony hazbun rhph 406d hazbun@pharmacy.purdue.edu –include mcmp 422 in the subject line

MCMP 422

• Tony Hazbun

• RHPH 406D

• Hazbun@pharmacy.purdue.edu– Include MCMP 422 in the subject line

MCMP422

Immunology

• Immunology is important personally and professionally!

• Learn the language - use the glossary and index

• RNR - Reading, Note taking, Reviewing

• All materials in Chapters 1-5 are examinable (with exceptions) plus extra material from class

What and why?

• Immunology: Science of how the body responds to foreign agents

• Immune system: the organs, cells and molecules that defend and respond to pathogens/allergens

• Organ transplantation, cancer, immunodeficiency diseases, infectious diseases

Immunology

• How do we recognize foreign structures?

• How do we recognize self vs non-self?

• How do we stop and remove invading agents?

Pharmacy and Therapy Perspective

• How can we use the immune system as a therapeutic agent?

• How do drugs affect the immune system?

What components make up the immune system?Cells, organs, cytokines and other molecules involved in the

immune system

What is the goal of the immune system?To clear pathogens in our body

How do we classify immune responses?Innate and adaptive immune responses

What are the side effects of the immune system?Autoimmune diseases, Allergies, Transplantation Rejection

Chapter 1 Concepts

Machinery of the Immune system

1. Tissues/organs bone marrow, thymus, spleen, lymph nodes

2. Cells lymphocytes, dendritic cells, macrophages, natural killer cells, granulocytes (neutrophils, basophils, eosinophils), mast cells

3. Blood-borne proteins complement and mannose-binding proteins

Origin of Immunology - individuals who survived a disease seemed to be untouched upon re-exposure

Vaccination/Immunization - procedure where disease is prevented by deliberate exposure to infectious agent that cannot cause disease.

Vaccinia - mild disease caused by cowpox

Edward Jenner - first demonstration of vaccination

Figure 1-2

Pathogen - any organism that can cause disease

• Four Classes-Bacteria-Fungi-Viruses-Parasites

• Opportunistic pathogense.g. Pneumocystis carinii

• Pathogen-Host relationship

Diversity of Pathogens

Part of body BacteriaHead (scalp) 1,000,000 /cm2Surface of skin 1000 /cm2Saliva 100,000,000 /gNose mucus 10,000,000 /gFaeces over 100,000,000 /g

How Clean are You?

Defenses against Pathogens

Physical Defenses1. Skin

- Tough water-proof Barrier- Pathogen Penetration is difficult- Breached by wounds/mosquito

2. Mucosal surfaces- line body cavities- epithelial cells covered with mucus- mucus thick fluid layer containing glycoproteins, proteoglycans and enzymes- e.g. mucus in lungs traps pathogens

Immune Defenses1. Innate - physical defenses are part of innate immunity2. Adaptive

Physical Barriers

• Lungs: Mucus, cilia trap and move pathogens

• Nose: Mucus traps pathogens which are then swallowed or blown out

• Mouth: Friendly bacteria, Saliva

• Eyes: lysozyme

• Stomach: acid neutralization

• Intestine: Friendly bacteria

• Urogenital tract: Slightly acid conditions

Pathogen

Signal

Effector mechanisms

Effector Cells Complement

Immunity: Three Basic Parts

Recognition(Binding event)

(Foreign)

(Self)

Immunedisorders

Two types of Immunity - Innate or Adaptive

Innate Immunity

• Ancient system - present in invertebrates• naïve, immediate, everyday immunity

• Molecules recognize common features of pathogens– Lectin– Phagocytes, large lymphocytes (NK cells)– Complement

Adaptive Immunity

• Newer system - present in fish, birds, human

• specialized, late, immunity• Molecules recognize specific features of

pathogens– Antibodies– B and T cells - small lymphocytes– Immunological memory

Figure 1-5 part 1 of 2

Complement - blood borne (serum) proteins that tag pathogens or attack them directlyEffector cell - engulf bacteria, kill virus infected cells, attack pathogensEndocytosis - process by which extracellular material is taken up

Example of Innate Immunity

One type of effector cell is the phagocyte

Figure 1-6

Cytokines = signaling molecules --> inflammation/adaptive immunityPhagocytosis = “phagos” means to eatInflammation is sometimes an unwanted by-product!Inflammatory cells = WBC’s contributing to inflammation

Innate Immunity

Inflammation

• Inflammation - local accumulation of fluid and cells involved in the immune response

• What happens when inflammation is induced

1. Blood capillary dilation => heat (calor) & redness (rubor)- Local dilation of blood capillaries = increase of blood to the area

(DOES NOT increase blood flow)

1. Vascular dilation (vasodilation) => swelling (tumor) & pain (dolor)

2. Extravasation - movement of cells/fluid into connective tissue.A) change in adhesiveness of the endothelial tissue

allowing immune cells to attach and migrate into the connective tissue

B) vascular dilation - gaps in endothelial cells

Example of inflammation gone bad: Sepsis

Systemic inflammatory response syndrome (SIRS)

Results from the body's systemic over-response to infection

Treatment: broad-spectrum antibiotics and supportive therapy

Disturbance of innate immunity during sepsis and multiorgan dysfunction syndrome (MODS) probably linked to uncontrolled activation of the complement system

Future Drug therapies could be used that modulate pro-inflammatory and anti-inflammatory factors

Innate and Adaptive responses

Innate

Pathogen independent Immediate (hours)

NeutrophilsMacrophagesMast cellsEosinophilsBasophilsNK cells“Large Lymphocytes” = NK

cells

Adaptive

Pathogen-dependent Slower (days)

Dendritic cellsB cellsT cells (CD4 or CD8)“Small Lymphocytes” = B & T cells

Both systems “talk” to each other to modulate responseBoth systems use leukocytes = white blood cells

What if Innate Immunity is not Enough?

• Innate immunity keeps us healthy most of the time

• Some pathogens escape the innate immune process

• Need a specific system to adapt to a specific pathogen

- Hence vertebrates evolved the Adaptive immune response

Principles of Adaptive Immunity

1. Lymphocytes each with different specificity generated by gene rearrangements

2. Small fraction of total pool of lymphocytes can recognize the pathogen

3. Pathogen recognizing lymphocyte is amplified - Clonal amplification

4. Pathogen recognizing lymphocyte can persist providing long-term immunological memory

5. Primary vs Secondary immune responseeg. Influenza/Measles/Vaccination

Figure 1-7

Characteristics of Innate vs Adaptive Immunity

Leukocytes - white blood cells that increase the immune response to ongoing infection

INNATE ADAPTIVE

= genes are constant = genes are rearranged

Innate vs Adaptive Molecular Recognition

• Most important difference: Receptors used to recognize pathogens

• Innate immunity: Receptors recognize conserved structures present in many pathogens (usually a repetitive pattern)

Pathogen-associated Molecular Patterns (PAMPs): LPS, peptidoglycan, lipids, mannose, bacterial DNA and viral RNA

e.g. Mannose-binding Lectin (MBL)

• Adaptive immunity: Receptors recognize a specific structure unique to that pathogen

e.g. Antibodies

Figure 1-11 part 1 of 2Flowchart of Hematopoiesis

Pluripotent stem cellSelf-renewal

Figure 1-11Flowchart of Hematopoiesis

Leukocytes

Myeloid Lineage

Figure 1-9 part 3 of 6Neutrophils:Most abundantPhagocyteEffector cells of Innate ImmunityShort-lived - Pus

Eosinophils:Worms/intestinal parasitesAmplify inflammationBind IgEVery Toxic - Pathogen and hostChronic asthma

Basophils:RareUnknown functionBind to IgE

Granulocytes (Myeloid progenitor)Polymorphonuclear leukocytes (PMLs)

Figure 1-9 part 5 of 6• Circulate in blood• Bigger than PMLs• Look similar• Immature form of macrophage

• Scavengers• Phagocytose pathogens, cells, debris• Secrete cytokines

Figure 1-13

Macrophages respond by two mechanisms - use 2 different receptors.

1) Phagocytosis - Phagosome fuses with lysosome - toxic small molecules and hydrolytic enzymes kill/degrade the bacteria

2) Signaling - bacterial component binds receptor - initiates transcription - inflammatory cytokines synthesized and secreted

• Star-shape• In tissue• Cellular messenger• Cargo cell

• Connective tissue• Unknown progenitor• Granules• Degranulation major contributor to inflammation and allergies

Lymphoid Lineage Cells

Large lymphocytesNK cells

Innate immunity

Small lymphocytesB cellsT cells

Adaptive immunity

Figure 1-9 part 2 of 6

Lymp

• Large lymphocyte with granular cytoplasm• Effector cell of innate immunity

1) kill viral infected cells2) secrete cytokines that interfere with virus infections

• B cells have B cell receptors and secrete Ab

• T cells have T cell receptors

• Adaptive IR• Small and immature• Activated by pathogen• Two types

- B cell- T cell

Erythroid Lineage

Figure 1-9 part 6 of 6• Giant nucleus• Resident of bone marrow• Fusion of precursor cells• Fragments to make platelets

• Gas transport• Infected by Plasmodium falciparum

Lymphoid Myeloid Erythroid

Neulasta (Amgen): Granulocyte Colony-Stimulating Factor (G-CSF)Recovery from Neutropenia & protect against Bacterial disease

Leukine (Schering-Plough): Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF), Recovery from Neutropenia and protection against Bacterial/fungal/parasitic disease

Plasma

Red blood cells

White blood cells

Centrifuged blood sample

Figure 1-12

High WBC could be a sign of infection or leukemia

Low WBC bone marrow diseases or HIV

Polys = polymorphonucleocytes - mainly neutrophils

High lymphocyte count indicates the bacterial or viral infection

Figure 1-15

The lymph system and sites of lymphoid tissue

Primary (Red) and Secondary (yellow)GALT, BALT, MALTThoracic DuctLymphpatic vessels - fluid collectionLymph nodes - junctions of vessels

RecirculationDraining Lymph nodeEdema - is worse when patient is inactiveAfferent (entry)Efferent (exit)

Figure 1-17 part 1 of 2

Communications CenterAfferent vessels bring in the lymph from infected tissueEfferent vessels place of exit for non-activated lymphocytes

B-cell area(follicle)

Lymphocytes

T-cell area

artery

Activated by dendritic cell

T helper cell (lymph node) T helper cell

(Infection site)

Activate B cells

Make Antibodies

Activate Macrophages

Cytotoxic T cell (Infection site)

Kills infected host cells

Lymphocyte not activated

Efferent lymph

PathogenDendritic cells

Afferentlymph

Lymphocytes enter node through artery

Tcells migrate to the T-cell area and if they meet a dendritic cell that is carrying pathogens from an infection site they get activated - to divide into functional effector cells.

Some T-cells stay in the lymph node and become T-helper cells - secrete cytokines (soluble proteins) and have receptors that contact B-cells. This helps the B-cells differentiate into plasma cells.

Plasma cells stay in the lymph or leave and pump out large amount of antibodies - a soluble form of their cell surface receptor

A second type of activated T-cell is the T-helper cell that leaves the node to the infected area and interacts with macrophages and amplify inflammation

Third type of T-cell is the cytotoxic T-Cell which kill cells infected with pathogen

Remember 5 million lymphocytes are entering node every minute and only a few are activated in response to an infection.

Figure 1-19

Anatomy of immune function in the Spleen

• Blood filtering organ - remove old/damaged red cells (red pulp)• Blood-borne pathogens e.g. malaria• White pulp (Immune system) - similar to lymph node (except pathogens enter and leave by blood)

Figure 1-20

Activated lymphocytes

M cells

M cells - specialized cells lining mucosal epithelium that deliver pathogen => activate lymphocytes

Adaptive Immunity

1. Vertebrates only

2. Specificity- recognition modules - BCR, Ab and TCR- gene rearrangement is the source of diversity- clonal selection

3. Small lymphocytes- types and sub-types- functions

Recognition concept

Receptor or Antibody molecule

Antigen - structure recognized by an Ab, BCR or TCR

Epitope - particular sub-structure of the Ag that is bound

Affinity - how much a molecule likes to bind to a structure

B-cellsBCR is Immunoglobulin (Ig)Plasma cells - effector cells that secrete Ab

T-cellsTc = cytotoxic (CD8+)

TH = helper T-cells (CD4+)Th1 (inflammation)Th2 (help B-cells make AB)

Small lymphocyte sub-types

Recognition modules of Adaptive immunity

B cells T cells

B-cell receptor (BCR)

Antibody is a secreted form of BCR TCR is membrane bound

T cell receptor (TCR)

B-cells T-cell

Native vs Denatured

Antigen processing

Major Histocomp-atibility (MHC)

APC - Antigen Presenting Cells

Professional APC- macrophages- B cells-Dendritic cells

MHC I - all nucleated cells - intracelluar pathogens e.g. virus

MHC II - immune cells - APC - extracellular

MHC

Interact with cytotoxic T cells

Interact with helper T cells

MHC class I communicates with cytotoxic T cells (Tc cells)

Cellular ribosomes are subverted into making more virus proteins

Some of those proteins are degraded in the cytoplasm and transported to ER

MHC1 bind to these peptides and help to display them on the cell surface

Cytotoxic T cells = Tc cells, Cytotoxic T-lymphocytes (CTLs)

MHC class II communicates with TH cells (TH1 or TH2)

Also: Dendritic cells interact with naïve T-cells to initiate differentiation

Antibodies

Produced by B-cells

Humoral Immunity - Humor = “body fluids”

Passive immunity - serum transferred to another individual can confer passive reistance due to transfer antibodies

Parasite +

Mast cell

Inflammation

Mast cell activated

Expel and/or destroy

pathogen

• Neutralization• Opsonization• Inflammation

Parasitic infection

Antibodies

Principles of Adaptive Immunity

DiversitySpecificityMemorySelf-tolerance

Gene Rearrangement is the source of Diversity

Germline configuration - the exact form of genes you inheritSomatic cells - all the cells of the body except germ cells

Diversity1. Alternative combinations2. Imprecise joints3. Different types of chains4. B-cells - somatic hypermutation

All this can happen in the absence of antigen

Clonal Selection

1. Each cell = one receptor2. Millions of lymphocytes

are generated3. Small subset will

recognize a pathogen4. Proliferation and

differentiation5. Acquired immunity - the

adaptive immunity provided by immunological memory

Figure 1-22Antibodies are usually very specific

Few specific lympho

cytes

Many lymphocytes

Some memory lymphocytes

Concept Behind Vaccination

•Pre-industrialization infants built immunity naturally

•Post-industrialization polio rate increased in adults hence a need for vaccination

Polio Vaccine - Inactive vs Oral “live” version

VDPV - vaccine derived polio virus, cheap and easy to administer- mutations can lead to polio at extremely low rate- immunocompromized individuals can be carriers of VDPV

Principle of Self-tolerance

B-cells with BCR that bind to self will undergo Apoptosis

More complicated scheme of selection for T cells

Mechanism of Self-tolerance

Selection of T cells

1. Thymocytes - immature T-cells

2. Positive selection-Self MHC-cortex (epithelial cells)

3. Negative selection

Immunodeficiencies

Inherited deficienciese.g. Bubble boy disease

Stress induced nutrition, emotional

Pathogen caused deficienciesHIV - attacks CD4 T lymphocyte

Figure 1-32

• IgE

• IgG

• CD4 TH1

• CD8 CTL

Cells and molecules involved in Hypersensitivity Diseases

Insulin-Dependent Diabetes Mellitus

• Beta cells of the islets of Langerhans in the pancreas are attacked

• Symptoms don’t show up for a long time

• Infection by a specific virus has been correlated with higher rate of IDDM

• Some of the activated CTL and Th1 cells will attack the healthy beta cells• IDDM also has been correlated with certain polymorphisms (types) of the MHC molecule

Hygiene Hypothesis or Global Warming Hypothesis

Inflammatory Adaptive Immune Response