Immunology

Question 1

Untreated immune deficiency leads to…

Answer 1

…death from overwhelming opportunistic infection

Question 2

Primary Immune deficiency disorders

Answer 2

(Born with it)

Bruton’s disease

Congenital thymic aplasia (Di George Syndrome)

SCID - severe combined immune deficiency

Question 3

What is Bruton’s disease?

Answer 3

Congenital agammaglobulinaemia

Absence of B cells

No germinal centres, small tonsils

Maternal transfer of IgG protects baby for 6-9 months

Treated by gamma-globulin injections

• or patient dies from staph, strep + haemophilus influenzae

Question 4

Congenital Thymic Aplasia (Di George Syndrome)

Answer 4

Absence of T cells, no secondary antibody response

Patients cannot control viral infections

Fetal thymus transplant required

Question 5

SCID (severe combined immune deficiency)

Answer 5

T cells do not mature

Adenosine deaminase deficiency

Agammaglobulinaemia

Extreme susceptibility to infection

2 year survival time w/out Bone Marrow transplant

Question 6

Causes of Secondary immune deficiency

Answer 6

Irradiation

Cytotoxic drugs (suppress immune system)

Glucocorticoids

Question 7

Acquired Immune Deficiency Syndrome (AIDS)

Answer 7

HIV infecting + killing CD4 T cell = immune deficiency HIV lives inside T cells

Question 8

3 lines of defence against infection

Answer 8

Physical barriers (skin, mucus membrane)

Innate immune system (consists of phagocytes -phagocytosis)

Adaptive immune system (dependent on antigen receptors on lymphocytes; includes acquired)

Question 9

Clonal selection

Answer 9

ability to distinguish foreign, harmful antigenic threats (infection) from self - dependent on specific antigen receptors

ability to then amplify that response by selectively expanding the clone of the crosslinked B cell or T cell + protective manner to protect against infection

Question 10

Primary + secondary response

Answer 10

Question 11

Function of the Spleen

Answer 11

Control blood-borne infection

Question 12

T lymphocytes

Answer 12

Arise in bone marrow but mature in the thymus gland

Start immune responses - have antigen specific T cell receptor (CD3)

2 populations of T cells

• T helper
• Cytotoxic T lymphocytes

CD = cluster of differentiation = surface markers distinguishable by specific antibody reagents

Question 13

B cells

Answer 13

Differentiate into plasma cells + secrete antibodies

Function as a antigen-presenting cells (APCs)

Question 14

Antigen-presenting cells (APC)

Answer 14

Focus antigen onto the T + B cell antigen receptors causing a more powerful immune response

Question 15

Antibodies

Question 16

Classification of antibodies

Answer 16

Immunoglobulin M (IgM)

Immunoglobulin G (IgG)

Immunoglobulin A (IgA)

Immunoglobulin D (IgD)

Immunoglobulin E (IgE)

Question 17

What are antibodies?

Answer 17

Antibodies are also called immunoglobulins

They co-purify with the globulin fraction of plasma

There are 5 classes

Each class has a specific receptor on its surface called Fc receptor.

For phagocytosis to occur, antibodies crosslinked to antigen bind to Fc Region on phagocyte.

Question 18

Where is the receptor for IgE found?

Answer 18

On basophils + mast cells

They possess granules containing mediators e.g. histamine

Mediators are released after contact with allergen

Question 19

Chemokines + Cytokines

Answer 19

Act as chemical messengers

Question 20

MHC + antigen presentation

Answer 20

MHC is also known as Human Leukocyte Antigens (HLA)

Function of MHC is to present antigen to T cells to distinguish between self + nonself