Adaptive Immunity 2

Question 1

What are B cells?

Answer 1

• Produce antibodies
• Communicate with T cells
• Memory B cells important to mount a quicker antibody response to further infections

Question 2

Where do B cells mature and circulate?

Answer 2

Bone marrow, circulate in blood and lymph

Question 3

How do B cells recognise antigens?

Answer 3

B cell receptor (Immunoglobulin - antibody)

Question 4

How many types of immunoglobulins produced by B cells?

Answer 4

5

IgG, IgE, IgD, IgM, IgA

Question 5

What are the three main functions for antibodies (Immunoglobulins) in human body?

Answer 5

• Neutralisation
• Opsonisation (coating pathogens by antibodies or complement proteins to PROMOTE PHAGOCYTOSIS)
• Initiation of complement system (3 pathways; classical, alternative, mannose binding lectin pathway)

Question 6

Where does Negative selection occur in B-cells?

Answer 6

Bone marrow, macrophages will remove any self-reactive B cells

Question 7

What are the 2 types of B cell activation?

Answer 7

Thymus-dependent antigens: antigens which require T cell help

Thymus-independent antigens: antigens which DONT require T cell help

Question 8

What is avidity and affinity in antibodies?

Answer 8

Avidity = ability of antibodies to form complexes

Affinity = strength of binding of single antibody to antigen

Question 9

What role do T and B cells take part in the principles of vaccination?

Answer 9

Initial exposure leads to immunological memory.

Presence of memory B and T cells means upon second exposure, immune response much faster.

More effective IgG are produced rather than IgM (antibodies)

Question 10

What is tolerance?

Answer 10

A process which ensures the immune system does not attack self antigens - prevents AUTOIMMUNITY

Question 11

What is central tolerance?

Answer 11

The process of eliminating any T or B cells that are reactive to self (recognition of self antigen - negative selection)

B cells occurs in bone marrow, T cells occurs in thymus

Question 12

What is peripheral tolerance?

Answer 12

Prevents the ACTIVATION/PRIMING of self reactive T cells which haven’t been eliminated

Question 13

What happens when there is a breach of tolerance?

Answer 13

Reactivity against self antigens

Breach of tolerance to ‘self antigens’ or commensal organisms (antigens) results in many autoimmune diseases