IMMUNOLOGY

Question 1

OBJECTIVES

Answer 1

Define and contrast the terms “innate or natural” and “acquired or adaptive” immune
responses.
2. Classify the immune cells and relate their structures and components to their functions
in innate and adaptive immunity.
3. Identify the primary and secondary lymphoid organs and explain their differentiation
4. Briefly compare and contrast the structure of the thymus, lymph node, spleen and
Peyer’s patch.
5. Describe briefly with the aid of diagrams, the recirculation of lymphocytes.
6. Categorise the terms “humoral”,“cell-mediated”, “active” and “passive”immunity.
7. Describe with the aid of a simple diagram, the basic structure of the immunoglobin
molecule, identifying the antigen binding site and Fc portion of the molecule.
8. Identify the various immunoglobin classes and subclasses in humans, and relate their
individual structures to their functions.
9. Explain antigen, immunogen and antibody.
10. Outline the principles of the generation of antibody diversity.
11. Compare and contrast the following receptors: MHC, BCR and TCR, by their
structures and functions.
12. Outline the developmental pathway of the B-lymphocyte in the bone marrow and its
further differentiation after antigen stimulation.
13. Differentiate between primary and secondary antibody responses, relating the
importance of isotoype switching, affinity maturation and immunological memory
processes.
13
14. Outline the development of T-lymphocytes in the thymus and briefly describe positive
and negative selection.
15. Explain the differentiation of T lymphocytes into their various types and relate their
functional differences.
16. Illustrate the gene map of the Major Histocompatibility Complex. Draw simple
diagrams to illustrate the structure of MHC Class I and II molecules. Compare the
distribution of these molecules.
17. Outline the mechanisms for processing of antigens, the major APCs and their
locations.
18. Outline the stages of activation, proliferation and differentiation of T-lymphocytes in
response to presented antigen.
19. Describe the role of T-cells in cell-mediated cytotoxicity, macrophage activation,
delayed hypersensitivity and T-cell/B-cell co-operation.
20. Draw a simple diagram of the complement pathways. List the major functions of
complement giving examples of specific components mediating these effects.
21. Define an immune complex. Describe the role of immune complexes in antigen
clearance and the generation of inflammation. Outline the factors involved in the
removal of immune complexes.
22. Define the term “cytokine.” Describe the general properties of these molecules. List
the major cytokines involved in the acute phase response regulation of
haematopoiesis, phagocyte function and T-cell, B-cell and NK cell function.

Question 2

HOW DOES INFECTION GET IN

Answer 2

INFECTION GETS IN BY PHYSICAL BARRIER: SKIN, PH ,CILIA
MOLECULAR BARRIER: COMPLEMENT, INTERFERON

Question 3

PHYSICAL BARRIERS TO INFCETION

Answer 3

ADD IN PHOTO

Question 4

WHAT ARE THE FORMATION OF LEUCOCYTES

Answer 4

PHOTO

Question 5

HAEMATOPIOEIS CELLULAR DIFFERENTCIATION

Answer 5

PHOTO

Question 6

MULTIPOTENTIAL HAEMATOPOIETIC STEM CELL

Answer 6

Responsible for blood and immune cells (white blood cells)
1)Multipotent
2) Ability to differentiate into all functional blood cells
3) Self-renewal
4) Ability to give rise to HSC without differentiation

Question 7

COMMOM LYMPHOID PROGENITOR (CLP)

Answer 7

1-Earliest lymphoid progenitor cell
2-Gives rise to T, B and NK cells along with DCs

Question 8

B LYMPHOCYTE- B CELL

Answer 8

1- Named ‘B’ cell due to its location
2-Produces antigen specific immunoglobulins, aka, antibodies, against invasive pathogens.
3- Also presents antigens and secrete cytokines.

Question 9

T LYMPHOCYTE- T CELL

Answer 9

1- 2 LYMPHOCYTE CELL NAMED ‘T’ DUE TO ITS LOCATION OF MATURATION ( THYMUS GALND)
2-Various types exists with varying functions
3-Responsibilities include assisting B cells, production of cytokines, regulation of immune responses and killing of infected and cancerous cells

Question 10

NATURAL KILLER CELLS NK CELL

Answer 10

1- Functions include
Killing of virally infected cells
Detecting and controlling early signs of cancer
2-Designated as ‘ Natural’ as they don’t priming to kill infected cells unlike T cells

Question 11

COMMON MEYLOID PROGENITOR- CMP

Answer 11

Precursor of erythrocytes, thrombocytes, granulocytes,
monocyte-macrophages, dendritic cells, mast cells and osteoclasts

Question 12

MAST CELL

Answer 12

Long lived tissue resident cells
Functions include defense in parasitic infections and role in allergic reactions
Releases cytokines and inflammatory mediators

Question 13

MYELOBLAST

Answer 13

UNIPOTENT STEM CELL
DIFFERENTIATES INTO VARIOUS EFFECTOR CELLS

Question 14

BASOPHIL

Answer 14

Plays a role in:
Allergic reactions
Preventing blood clotting

Question 15

EOSINOPHIL

Answer 15

Plays a role in defense against parasites

Question 16

NEUTROPHIL

Answer 16

PHAGOCYTOSIS
BACTERICIDAL MECHANISMS

Question 17

MONOCYTE

Answer 17

Phagocytic cells found in the blood stream
Matures into macrophages upon migration to tissues

Question 18

MACROPHAGE- MAC

Answer 18

Phagocytosis
Bactericidal mechanisms
Antigen presentation

Question 19

DENDENTIC CELLS

Answer 19

Antigen presentation
Initiation of activation of B and T cells

Question 20

LYMPHOID ORGANS

Answer 20

PHOTO
Broadly subdivided into
Primary/Central Lymphoid Organs
Lymphocytes are generated
Ag cannot enter in
Secondary/Peripheral Lymphoid Organs
Adaptive immune responses are initiated
Lymphocytes are maintained
Ag can enter in

Question 21

PRIMARY LYMPHOID ORGANS

Answer 21

Primary 2 Bone Marrow and Thymus
B and T cells originate in BM
Only B cells mature there; precursor T cells migrate to the thymus and undergo maturation there.
Mature B and T cells enter the bloodstream and
migrated to secondary/peripheral lymphoid organs:
Antigen cannot enter into these organs
They atrophy with age

Question 22

SECONDARY LYMPHOID ORGANS

Answer 22

Specialized to:
- trap Ag-bearing dendritic cells
- Allow initiation of adaptive immune responses
- Provide signals that sustain recirculating
Lymphocytes
- Antigen can enter in
- Increase in size with age
- Includes
- Lymph nodes
- Spleen
- GALT, BALT & MALT

Question 23

SECONDARY LYMPHOID ORGANS

Answer 23

Lymph nodes:
- Located at points of convergence of vessels of the lymphatic system
- Afferent lymphatics carry Ag-bearing cells from infected tissues to the LNs
- In LNs, B cells are localized in follicles while T cells are diffusely distributed
- This organization promotes interactions between APCs and T cells and between activated Ag-specific T cells and B cells
upon encountering Ag.

Question 24

SECONDARY LYMPHOID ORGANS

Answer 24

+ Spleen
+ Collects Ag from the blood
+ Gut-associated lymphoid tissue
+ Includes tonsils, adenoids, appendix and patches in the small intestine

+ In 3H\HU·V patches, Ag collected by specialized epithelial cells: multi-
fenestrated or M cells

+ Bronchial-associated lymphoid tissue
+ Protects the respiratory epithelium
+ Mucosal-associated lymphoid tissue
+ Protects other mucosa

Question 25

INNATE (EARLY) AND ADAPTIVE (LATER) BOTH HAVE ALPHA T CELL/ NK T CELL

Answer 25

INNATE IMMUNITY- RAPID RESPONSE CELLS INCLUDES: DENDENTIC CELL, MAST CELL,MACROPHAGES, NK CELLS, COMPLEMENT PROTEIN, EOSINOPHIL, NEURROPHIL, BASOPHIL, GRANDULOCYTES

Question 26

INNATE (EARLY) AND ADAPTIVE (LATER) BOTH HAVE ALPHA T CELL/ NK T CELL

Answer 26

INNATE IMMUNITY- RAPID RESPONSE CELLS INCLUDES: DENDENTIC CELL, MAST CELL,MACROPHAGES, NK CELLS, COMPLEMENT PROTEIN, EOSINOPHIL, NEURROPHIL, BASOPHIL, GRANDULOCYTES. ADAPTIVE IMMUNITY (SLOW RESPONSE) B CELL, T CELL- CD4+ CD8+, ANTIBODIES

Question 27

Innate (Early) Immune System

Answer 27

The Innate Immune System Detects pathogen-associated molecular patterns (PAMPs) on surface of microbes via receptors called Pattern Recognition Receptors (PRRs) Protects against infection by removing the infectious agent Microbes are able to evade innate defense systems by changing their structure

Question 28

POINTS OF ENTRY CELL TISSUES ORGANS

Answer 28

PHOTO THYMUS, SPLEEN, LYMPH NODES, TONSILS AND ADENOIDS, LYMPH NODES, PEYER'S PATCH, BONE MARROW

Question 29

Pathogen Associated Molecular Patterns = PAMPs

Answer 29

PHOTO PARASITES- HELMINTHS- TAPEWORM PROTOZOA- PLASMODIA-MALARIA FUNGI- TINEA-ATHLETE'S FOOT PROKARYOTE- BACTERIA- LEPROSY VIRUS- HIV- AIDS PRION-CJD

Question 30

Pathogen Associated Molecular Patterns = PAMPs

Answer 30

BACTERIS GRAM +IVE AND -IVE> LIPOTEICHOIC ACID( LTA), PEPTIDOGLYCAN (PGN), LIPOPROTEINS, DNA, FLAGELLIN, LIPOPOLYSACCHARIDES (LPS) VIRUS- COAT PROTEIN, NUCLEIC ACID PARASITE- GPI ANCHOR YEAST- ZYMOSAN (BETA-GLUCAN)

Question 31

Pattern Recognition Receptors = PRRs

Answer 31

PHOTO CLR NLR TLR RLR

Question 32

WHAT IS INFLAMMATION

Answer 32

Clinically : The presence of redness, swelling and pain Histologically: The presence of oedema fluid and the infiltration of tissues by leucocytes Immunologically: Part of the non-specific immune response that occurs in reaction to any type of bodily injury

Question 33

ACUTE AND CHRONIC

Answer 33

Some infections cannot be cleared 2 Chronic inflammation e.g. Tuberculosis, Hepatitis B Acute & Chronic Inflammation Mechanisms for responding to infections Contributors to autoimmune disease

Question 34

WHAT ARE THE SIGNS OF INFLAMMATION

Answer 34

PHOTO

Question 35

5 CARDINAL SIGNS OF INFLAMMATION

Answer 35

PAIN HEAT REDNESS SWELLING LOSS OF FUNCTION

Question 36

ACUTE INFLAMMATION

Answer 36

Last a few days Lasts days to a few weeks Clearance highly dependent on Innate Immune system +/- help from adaptive immune system E.g. Acute reactions to extracellular bacteria result in pus formation 2 they are Pyogenic The yellow color is due to neutrophil granules. Pus develops over a few hours If the offending stimulus cannot be removed, the inflammation becomes chronic

Question 37

CHRONIC INFLAMMATION

Answer 37

Occurs when. Infection difficult to clear. E.g. Chronic intracellular bacterial infection may lead to the formation of granuloma ( chronic inflammatory lesion) Persistence of foreign material, e.g. some types of sutures Immune system is attacking self tissue (autoimmune disease) Excessive formation & deposition of endogenous material, e.g. urate crystals in gout T cells and macrophages are main cells in chronic inflammatory lesions as Granulomas Adaptive immune response drives chronic inflammatory responses

Question 38

WHAT ARE CYTOKINES

Answer 38

Soluble, low-molecular weight regulatory proteins/glycoproteins secreted by cells, mainly leucocytes, in response to stimuli, acting as intercellular mediators or signaling molecules. CYTOKINES CAN Initiate acute inflammation Maintain chronic inflammatory responses Bind to specific receptors on target cells Trigger signal-transduction pathways Alter gene expression Regulate the intensity and duration of the immune response Stimulate or inhibit the activation, proliferation and/or differentiation of various cells Regulate the secretion of Abs and other cytokines Secreted transiently and their receptors are often expressed transiently Binding of a cytokine to its receptor stimulates increased expression of the receptor and other cytokines

Question 39

INDUCTION AND FUNCTION OF CYTOKINES

Answer 39

PHOTO

Question 40

WHAT ARE THE ACTIONS OF CYTOKINES( WORK IN NETWORKS)

Answer 40

PHO

Question 41

A guide thru an immune response

Answer 41

Inflammation can also be triggered by activation of complement. Complement coats microbial surfaces with fragments that are recognised and bound by phagocytic receptors on macrophages Cytokines and complement fragments cause circulating leucocytes to migrate to site of infection, chemokines attract them there. What is Complement?

Question 42

COMPLEMENT SYSTEM

Answer 42

A molecular barrier of the innate immune system Nine basic complement components C1 to C9 Once activated, nine components split into smaller fragments Three pathways of Complement Classical Alternative Lectin

Question 43

Physiologic - Extracellular Molecules - Complement

Answer 43

PHO

Question 43

Physiologic 2 Extracellular Molecules 2 Complement Classical Pathway

Answer 43

PHOTO Activated by IgG2 (IgG1, IgG2, and IgG3 but not IgG4) or IgM2containing immune complexes through binding by C1q. C1qrs is then assembled and cleaves complement components C2 and C4 to form the C4b2a enzyme complex, a C3 convertase. Regulatory factors MCP 2 membrane co- factor protein DAF 2 decay accelerating factor CD59 2 Prevents C9 from completing MAC

Question 44

Physiologic 2 Extracellular Molecules 2 Complement Classical Pathway

Answer 44

PHOTO Activated by IgG2 (IgG1, IgG2, and IgG3 but not IgG4) or IgM2containing immune complexes through binding by C1q. C1qrs is then assembled and cleaves complement components C2 and C4 to form the C4b2a enzyme complex, a C3 convertase. Regulatory factors MCP 2 membrane co- factor protein DAF 2 decay accelerating factor CD59 2 Prevents C9 from completing MAC

Question 45

Physiologic 2 Extracellular Molecules 2 Complement Lectin Pathway

Answer 45

PHOTO 1) Activation of the lectin pathway is on the basis of recognition of microbial cell surface carbohydrates by mannan-binding lectin (MBL) or ficolin. Lectin- carbohydrate binding protein Ficolin- oligomeric lectins MASP- MBL- associated serine proteases 2) MBL binds to mannose residues which activates MASP1 & MASP2 3) This process leads to cleavage of C2 and C4 to form the classical pathway C3 convertase C4bC2a.)

Question 46

what is the complement cascade

Answer 46

photo

Question 47

ALTERNATIVE PATHWAY TO THE COMPLEMENT SYSTEM

Answer 47

PHOTOS The alternative pathway activates complement on the surface of any cell that lacks complement inhibitors, whereas the lectin and classical pathways provide focused complement activation to molecules that have been bound by MBL or antibody.

Question 48

ANTIGENS

Answer 48

Antigen- a substance that induces an immune response. Parts of an antigen are recognized by receptors of the adaptive immune system. Can be classified via how they induce an immune response and their origins Name the different types of antigens

Question 49

ANTIGENS

Answer 49

PHOTO OF THE INNATE ADAPTIVE IMMUNITY PG 62 INNATE IMMUNITY- MICROBE - EPITHELIAL BARRIER, NEUYROPHIL, MACROPHAGES, NK CELL, COMPLEMENT, NATURAL ANTIBODIES ADAPTIVE IMMUNITY- B LYMPHOCYTE, HELP T LYMPHOCYTE,CYTOTOXIC T YMOHOCYTE, HIGH AFFINITY ANTIBODIES

Question 50

THE ADAPTIVE IMMUNITY SYSTEM

Answer 50

T and B lymphocytes 2 main immune cells Large numbers of pre-existing receptors expressed on lymphocytes 2 potential to bind with any foreign Ag entering the body Three groups of molecules specifically recognize foreign Ag: T cell receptor (TCR) B cell receptor (BCR) Major Histocompatibility complex (MHC) 2 the cluster of genes is known as human leukocyte Ag (HLA) in humans

Question 51

THE ADAPTIVE IMMUNE SYSTEM

Answer 51

7DQG%FHOOVμVHHμ antigen differently B cells can bind directly with bits of the antigen T cells see bits of antigen bound to MHC molecules Antigen presenting cells " chew: antigen and put these fragment into MHC molecules on their surfaces. fragment into MHC molecules on their surfaces

Question 52

Physiologic 2 Extracellular Molecules 2 Complement Alternative Pathway

Answer 52

photo 1) Initiated constantly by spontaneous hydrolysis of C3, leading to the formation of C3(H2O)Bb, which cleaves C3 into C3a and C3b. 3) Amplification of this pathway is on the basis of the covalent binding of C3b to activating surfaces (e.g., bacterial surface) followed by cleavage of factor B (FB). 3) In the presence of factor D and properdin, this process leads to formation of the alternative pathway C3 convertase (C3bBb). 4) Properdin promotes association between C3b and FB, thus stabilizing the alternative pathway C3 convertase (C3bBb). Regulatory factors - Factor H - Factor I - CR1

Question 53

Antibodies ( serum Ig )

Answer 53

photo

Question 54

MHC l AND ll CLASSES

Answer 54

photo

Question 55

immunoglobulin (IgG)

Answer 55

photo

Question 56

antibodies

Answer 56

photo of the five different classes of an antibodies The five different classes of human heavy chains have slightly different structures. Each class is designated by lowercase Greek letters: - IgMǍ- IgM - IgD - IgG - IgE - IgA

Question 57

TCRs 2 classes of T- cell receptor

Answer 57

photo pg 69 antigen-binding site alpha and beta chain

Question 58

IMMUNOLOGIC MEMORY

Answer 58

Long-term immunologic memory 2 capacity to generate an enhanced and more effective immune response to an Ag encountered in the past . Naïve B cells activated by Ag differentiate in Plasma Cells that secrete Ab In a primary response the plasma cells secrete a relatively low affinity Ab In a secondary response a higher affinity Ab is secreted -

Question 59

IMMUNOLOGIC MEMEORY

Answer 59

PHOTO 71 Primary response Secondary Response Time period to response 5 2 10 days 1 2 3 days Antibody class Mainly IgM IgG, IgA or IgE Affinity for Ag Low High