PH3113 - Pain and Analgesia 9

Question 1

What is an antibody?

Answer 1

An antigen-binding immunoglobulin, produced by B cells, that functions as the effector in an immune response

Question 2

What is a B lymphocyte?

Answer 2

Population of cells that express clonally diverse cell surface immunoglobulin (Ig) receptors
- B cell receptors
- BCR
- recognise specific antigenic epitopes

Question 3

What are single antibody genes made from?

Answer 3

Variable region
Diversity region
Joining region
Constant region

Each region is found on a different chromosome

Question 4

What is an epitope?

Answer 4

The part of an antigen molecule to which an antibody attaches itself

Question 5

What is the B cell receptor?

Answer 5

Bind B cell antigens
- B cells activated and plasma cells produce antibodies
- antigen receptor on B lymphocytes (B cell receptor (BCR)) is a cell-surface immunoglobulin

Question 6

What is a B cell co-receptor?

Answer 6

Co-stimulation of B cells is notable achieved by the molecule CD40
- CD40 ligand expressed on T cells
- CD40L

Question 7

What does the T cell activation CD40L interaction with B cell CD40 ligand release?

Answer 7

Cytokines
- TNF alpha
- causes cell to divide and proliferate
- some stimulated B cells become plasma cells
- secrete antibodies
- some become memory B cells

Question 8

What is the basic structure of an antibody?

Answer 8

Variable region
- antigen binding fragment (Fab) recognises the antigen
Fc fragment
- recognises specific Fc receptors on effector cells

Question 9

What are the classes of antibodies?

Answer 9

IgA
- dimer
- prevents attachment of pathogens to epithelial cell surfaces
IgD
- monomer
- attach to surface of B cells
- B cell activation
IgE
- monomer
- binds to mast cell and basophils
- degranulation
- histamine release
IgG
- monomer
- most abundant and diverse antibody
- primary and secondary response
- crosses the placenta
- passive immunity
IgM
- pentamer released by plasma cells
- primary antibody response

Question 10

What are the effector functions of antibodies?

Answer 10

B-lymphocytes surface receptor for antigen
- IgM
Neutralisation of antigen
- IgG
- IgM
- IgA
Opsonisation
- IgG
- IgM
Steric hindrance interaction of injurious material with host cell membrane
- IgG
- IgM
- IgA
Activation of complement
- IgG
- IgM
Mucosal immunity
- IgA
Activation of Mast cells triggered by
- IgE
Neonatal immunity mediated by maternal
- IgG
Antibody-dependent cell-mediated cytotoxicity

Question 11

What is antibody-dependent cell-mediated cytotoxicity (ADCC)?

Answer 11

Natural Killer cells, neutrophils, eosinophils as effector cells can
- lyse
- promote cell death of a target cell that is bound by antibody
- IgG
- effect cell, expressing Fc receptors on its surface, will bind to the Fc domains of antibody bound to target cell
NK cells kill target by apoptosis

Question 12

What is autoimmunity?

Answer 12

Immune response against self (auto) antigen
- pathologic

Question 13

What are the general principles of autoimmunity?

Answer 13

Pathogenesis
- development of autoimmunity reflects a combination of susceptibility genes and environmental triggers
- usually infections
Different autoimmune diseases
- systemic
- organ specific
- antibody
- T cell-mediated

Question 14

What is self-tolerance?

Answer 14

The ability NOT to react to proteins and other organic molecules our cells produce

Question 15

What are the central mechanisms for self-tolerance?

Answer 15

Deletion of lymphocytes reacting to self
- clonal deletion in thymus or bone marrow of lymphocytes reacting to self-antigen

Question 16

What are the peripheral mechanisms for self-tolerance?

Answer 16

Anergy - describes direct induction of peripheral lymphocyte tolerance
- endothelial barrier segregates T cells from self-antigens
- low levels of antigen will render B cells unresponsive by down-regulation of surface IgM expression
- B cells are short lived
- clonal anergy

Question 17

What is myasthenia gravis?

Answer 17

Progressive muscle weakness caused by auto-antibodies against acetylcholine receptors in motor end plates of neuromuscular junctions
Interferes with acetylcholine neuromuscular transmission
- may lead to reduction in number of receptions as a result of increased endocytosis
Results
- failure of muscle to respond to normal neural impulses
- progressive muscle weakness
Treatment
- anticholinesterases
- prolong action of acetylcholine by inhibiting acetylcholinesterases
- corticosteroids
- azathioprine

Question 18

What is Hashimoto’s disease?

Answer 18

An autoimmune cause of hypothyroidism
Thyroid gland bearing receptors for Thyroid Stimulating Hormone (TSH)
Interior surface filled with thyroid colloid
- mainly thyroglobulin and membrane bound enzyme thyroid peroxidase (TPO)
TSH interacts with its receptor to upregulate TPO
- increase synthesis of thyroxine and triiodothyronine
- released into circulation

Hashimoto’s thyroiditis
- thyroglobulin and TPO are two major antigens
- anti-thyroglobulin antibodies found in 95% of patients with Hashimoto’s disease

Question 19

What is Graves’ disease?

Answer 19

An autoimmune cause of hyperthyroidism
- rapid pulse
- fatigue
- muscle weakness
- tremors
- heat intolerance
- goitre
- myxedema
- suppressed TSH
- raised T4/T3
- antibodies against the TSH receptor