Key Concepts

Question 1

What are CYTOKINES?

Answer 1

messenger molecules (immune regulators)
e.g. Interleukins, Interferons, Colony stimulating factors, Tumour necrosis factors

Question 2

What are CHEMOKINES?

Answer 2

(chemotactic cytokines) - traffic control

Question 3

What is CHEMOTAXIS?

Answer 3

Unidirectional movement of cells along a concentration gradient of chemotactic molecules e.g. chemotactic cytokines, products of the complement system, lipid derived inflammatory mediators, microbial products

Question 4

What is IMMUNITY?

Answer 4

State if protection from pathogens e.g. recognition & response, self vs non-self

Question 5

When does RECOGNITION occur?

Answer 5

1. common molecular patterns on pathogens -(non specific - (natural/innate immunity))
2. subtle variations between pathogens - (specific - (adaptive immunity))

Question 6

What do MEMORY responses do?

Answer 6

Provide long term immunity

Question 7

What is INNATE immunity?

Answer 7

-present from birth
-rapid initial response (acute inflammatory response)
-Non-specific (PAMPs & DAMPs)
-Phagocytic cells
-Natural killer cells
-Mast cells
-Interferons (IFN-alpha & IFN-beta)
-The complement system

Question 8

What is ADAPTIVE immunity?

Answer 8

-Develops through exposure to pathogen
-Slow primary response
-Rapid memory response
-Specific
- B & T lymphocytes

Question 9

INNATE RECOGNITION

Answer 9

-Tissue leukocytes are involved in recognition of microbes
-Leukocytes express PRRs
-PRRs recognise PAMPs = integral to pathogen & common across species
-PRR binding triggers initial activation of innate immune response
-Innate response may lead to an adaptive (specific) response

Question 10

ACRONYMS

Answer 10

• PRRs - Pattern Recognition Receptors
  -PAMPs - Pathogen-Associated Molecular Patterns
  -TLRs - Toll Like Receptors
  -NLRs - NOD-Like Receptors
  -RLRs - Rig-Like Receptors
  -CDS - Cytosolic DNA Sensors
  -MHC - Major Histocompatibility Complex

Question 11

Pattern Recognition Receptors Summary

Answer 11

• They are expressed on a range of immune cells
  -Interaction with pathogen triggers the initial innate immune response
  -They are found on the surface and internal membranes

Question 12

Cell Killing process

Answer 12

-Neutrophils undergo phagocytosis of pathogens
-Macrophages & DCs also process antigenic material (antigen processing) for recognition by T cells
-Leads to an adaptive specific immune response

Question 13

What is the initial process of ADAPTIVE IMMUNITY

Answer 13

-Persistent antigens (Ag) move to the lymph nodes (LNs)
-LNs –> site of first adaptive immune response
-LNs are junctions between the blood circulation & drained tissue lymphatic fluids
-Lymphocytes leave blood to enter LNs
-Ag drained from the tissues enter B&T lymphocytes for the first time in LNs

Question 14

SPECIFIC RECOGNITION (Adaptive)

Answer 14

-Involves B&T lymphocytes
-Cells possess antigen-specific receptors
-One receptor per cell = monospecific
-Antigen(Ag): any material which induces specific responses
-B cells: specific membrane-bound antibodies e.g. immunoglobulins -
-T-cells: T-cell receptors (TCRs)

Question 15

T-cells

Answer 15

Only recognise processed antigenic proteins expressed on MHC molecules on self-cells

Question 16

B-cells

Answer 16

Antibodies interact directly with epitopes

Question 17

EFFECTOR B LYMPHOCYTES

Answer 17

-Following Ag exposure, effector B cells = plasma cells –> produce soluble antibodies
-Antibodies found in the blood circulation & various tissue fluids
-Secreted antibodies bind to Ag (not directly cytotoxic, labels Ag for destruction - recruiting other immune cells)

Question 18

Effector T Lymphocytes

Answer 18

-Different types of T cells (T-helper cells TH, Cytotoxic T cells Tc, Regulatory T cells T-reg)
-Effector TH cells = major producers of cytokines to enhance immune activity
-Effector TCs = kill abnormal self-cells (virally-infected cells, tumour cells)

Question 19

EFFECTOR RESPONSE

Answer 19

1.Humoral response - flags antigens for destruction, blocks spread of infection
2.Cell-mediated response - recognition, killing of infected cells

Question 20

IMMUNOLOGICAL MEMORY

Answer 20

-Central feature of adaptive (specific) immunity leading to life-long immunity to a pathogen
-Develops through exposure to a pathogen
-Involves clonal expansion of specific B&T cells, and memory cells
-Memory response is rapid and aggressive
-Establishing immunological memory is the primary objective of vaccination

Question 21

CLONAL EXPANSION

Answer 21

-Upon binding Ag, specific B&T cells undergo rapid cell division
-Multiple copies of the Ag-primed cells are formed = clonal population
-Process is driven mainly by T-helper cell cytokines
-Gives rise ton effector B&T cells, and memory B&T cells

Question 22

INATE IMMUNITY

Answer 22

Non-specific initial rapid response to infection and/or tissue damage
-Triggers an acute inflammatory response
-Quite destructive in nature
-Involves PRRs & PAMPs

Question 23

ADAPTIVE IMMUNITY

Answer 23

specific immunity - develops on Ag encounter with B&T cells
-Recognises epitopes present on the antigen
-Amplifies & focuses immune responses
-Generates immunological memory