Overview Of Adaptive Immunity

Question 1

Why do we have an adaptive immune system?

Answer 1

Some pathogens often come back and attack again - opportunity to have effectors ready

Some pathogens stick around - need controlling

Question 2

How do we recognise pathogens?

Answer 2

Generic recognisable features- PAMPS

They’re presence is associated with damage - damage associated molecular pattern molecules (DAMP)

Memory of past infection

Not familiar - autoimmunity - organ rejection

Question 3

What is the problems with predicting the unpredictable?

Answer 3

Over and under assiduous recognition

Self recognition

Question 4

What is a reactivated infection?

Answer 4

Low CD4 count has allowed “opportunistic infection” to get through the immune defences that should control it

Question 5

What are examples of diseases caused by B cell deficiency?

Answer 5

Common variable immunodeficiency (CVID)

Question 6

What are examples of diseases caused by T cell deficiency?

Answer 6

Severe combined immunodeficiency (SCID)

Acquired - HIV/chemotherapy

Question 7

What are the ways we can define lymphocytes?

Answer 7

Morphology - white cell, small, largeb

Lineage - T cell and B cell

Location - tissue resident and marginal zone

Differentiation - memory, mature, immature, differentiated

Function: what they do - helper, cytotoxic, antibody producing

Question 8

What factors define a lymphocyte?

Answer 8

Phenotype: what surface markers they express

Specificity- what target

Type of receptor

By what they produce

Question 9

How does adaptive immunity work?

Answer 9

Specificity

Memory

Question 10

What is clonal selection?

Answer 10

One cell - one specificity

Question 11

Describe clonal selection for B cells

Answer 11

One cell - one immunoglobulin (ig)

Defined by their antibody

May class switch/ undergo affinity maturation

But always the same basic ig

Question 12

Describe clonal selection for T cells

Answer 12

One cell - one T cell receptor

Selection and expansion of that clone and differentiation

Retention in “memory” of clonal progeny

Question 13

Which clonal cells provide continuous production of antibodies?

Answer 13

B cells

Plasma cells

Question 14

Which clonal cells provide a more rapid specific secondary response?

Answer 14

B and T cells

Question 15

What is a defining feature of a lymphocyte?

Answer 15

The specific receptor - variable reigons

Question 16

How do antigen presenting cells express the specific antigen?

Answer 16

Specialised antigen presenting cells process and present peptides on MHC-1

Recognised by CD8 cells through they’re TCR

Bind to TCR on CD4 T cells

Question 17

What is positive thymic selection of T cells?

Answer 17

Must bind MHC

Question 18

What is negative thymic selection of T cells?

Answer 18

Must not bind to self peptides

If it binds to self proteins too much the cells die

Question 19

How are naive cells maintained?

Answer 19

They just float around in the blood and lymph nodes

Question 20

Why do naive T cells have slow turn over rates?

Answer 20

They remain in active until a very strong antigen binds to its receptor

Then they differentiate into other T cells

Question 21

What are effector memory cells TEM?

Answer 21

Short lived population

Continually replenished

Doubling time about 15 days

Question 22

What are central memory cells TCM?

Answer 22

Turnover at a significant rate

Doubling time about 48 days

Question 23

How are B cells selected?

Answer 23

Posative/negative selection

Transition to IGN and IGD and mature B cell

Receptor editing

Activated B cells transform into plasma cells

Antigen recognition leads to proliferation/differentiation

Question 24

Describe the anatomy of lymphocytes

Answer 24

Organised mainly into lymph nodes - archetecbture optimised to facilitate cellular interaction

Question 25

What important role does the spleen play in antibody production?

Answer 25

Splenectomy increases risk of infection

Especially pneumococcal infection