Pathology L17 Mediators of Immunity

Question 1

Define: pleiotropism, redundancy, synergy, antagonism

Answer 1

Pleiotropism -> activate numerous types of responses - differentiation, growth, activation and chemotaxis
Redundancy -> functional overlap
Synergy -> between cytokines to optimise response
Antagonism -> to regulate duration and potency of response in order to prevent autoimmunity

Question 2

What are cytokines?

Answer 2

Secreted proteins that mediate and regulate immunity (innate and adaptive immunity) and inflammation

Question 3

Cytokines can act in an autocrine, paracrine and endocrine manner. What are these?

Answer 3

Autocrine - acts on cell that synthesized them
Paracrine - cells in the immediate environment
Endocrine - distant cells - similar to hormone

Question 4

What are the 3 types of interferon?

Answer 4

IFN alpha/beta/gamma

Question 5

What is the purpose of colony stimulating factor (CSF)?

Answer 5

Differentiates bone marrow cells to particular cells but can also have effects on mature cells

Question 6

What are chemokines?

Answer 6

Small proteins with 2 internal disulfide brides and conserved structure that act as chemoattractants when bound to a specific receptor - help cells move to SPECIFIC places

Question 7

Is the direction of chemotaxis towards higher or lower chemokine concentration?

Answer 7

Higher

Question 8

What are the 4 families of chemokines and what differentiates them?

Answer 8

C, CC, CXC, CXXXC - categorised based on spacing of the 2 cysteines

Question 9

What are complement proteins?

Answer 9

Heat labile plasma proteins activated in under certain situations that act as effector mechanisms for the innate immune system and humoral adaptive immune system

Question 10

What 5 functions do complements perform in innate host defence?

Answer 10

Innate: Opsonisation, Initiate inflammatory response, Clearance of apoptotic debris

Adaptive: B-cell activation, T-cell priming

Question 11

What are the 3 major pathways of the complement system?

Answer 11

Classical (antibodies), Alternative (bind to microbe), Lectin (bind to mannose)

Question 12

Which is the MAIN complement protein common to all pathways that INITIATES late steps of the process?

Answer 12

C3b

Question 13

In a clinical complement assessment, which two complement proteins are measured?

Answer 13

C3 and C4 serum levels

Question 14

Are high C3 levels pathogenic?

Answer 14

No, mostly part of the acute phase response

Question 15

What is the most likely infection to result from lack of C5-9 function?

Answer 15

Neisserial bacterial infection

Question 16

Do antigen presenting cell produce cytokines?

Answer 16

Yes aka dendritic cells, B cells, macrophages all produce cytokines

Question 17

What are some of the roles cytokines help with?

Answer 17

• Antigen recognition in lymphoid organs
• T-cell expansion and differentiation: each step of the T-lymphocyte life cycle is regulated by a cytokine
• Supporting effector phase of T-cell response

Question 18

What are the five cytokine families?

Answer 18

Interleukins
Interferons
TNFs
Colony Stimulating factors
Growth factors