Intro to Immunology

Question 1

Type 1 interferons

Answer 1

(IFNα and IFNβ) are produced by cells that have become infected with a virus.

Question 2

Type 2 interferon

Answer 2

(IFNγ) is released by activated TH1 cells.

Question 3

Antibodies and a link to phagocytes

Answer 3

The constant region of the antibody (the Fc region) can bind to Fc receptors on phagocytes, so acting as an adapter between the phagocyte and the pathogen.

Consequently, if antibody binds to a pathogen, it can link to a phagocyte and promote phagocytosis.

Question 4

SCID

Answer 4

no lymphoid precursor cells. Combined B and T cell immunodeficiencies. Recurrent infections with a wide range of pathogens.

Question 5

Bruton’s

Answer 5

low to no immunoglobulin in the serum, but normal T cells which do respond to mitogens.
AIDS

Question 6

Wiskott

Answer 6

bacterial infections. B and T cells affected. Progressive decline in lymphocytes over time. In early stages, people seem normal.

Question 7

basophil differentiation

Answer 7

CFU-GEMM

CFU-B

Question 8

Dendritic Cell Differentiation

Answer 8

CFU-GEMM
IL-3, GM-CSF
M-CSF, GM-CSF, IL-3 to monocyte
GM-CSF, IL-4

Question 9

Macrophage Differentiation

Answer 9

CFU-GEMM
IL-3, GM-CSF
M-CSF, GM-CSF, IL-3 to monocyte
M-CSF, GM-CSF

Question 10

What decides if a monocyte goes dendritic or macro?

Answer 10

Both get GM-CSF
IL-4 makes dendritic
M-CSF makes macro

Question 11

Neutrophil differentiation

Answer 11

CFU-GEMM
IL-3, GM-CSF
G-CSF, GM-CSF, IL-3

Question 12

Eosinophil differentiation

Answer 12

CFU-GEMM
CFU-Eo
GM-CSF, IL-3, IL-5

Question 13

Human Blood Monocyte

Answer 13

Large (10-18µm in diameter) relative to the lymphocyte.
Horseshoe shaped nucleus.
Contains primary azurophilic (blue-staining) granules.
Possess ruffled membranes, a well-developed Golgi complex, and many intracytoplasmic lysosomes.
The lysosomes contain peroxidase and several acid hydrolases, which are important for killing phagocytosed microorganisms. Monocytes/macrophages actively phagocytose microorganisms (mostly bacteria and fungi) and the body’s own aged and dead cells, or even tumor cells.
Long-lived (months to years).

Express:
CD14 (binds LPS)
MHC class II
CD11a and b (adhesion molecules)
CD64 and CD32  Fc receptors (bind antibodies)

Question 14

Polymorphonuclear Granulocyte

Answer 14

Released from the bone marrow at a rate of 7 million cells per minute.
Short-lived (2-3days)
Like monocytes, PMNs marginate (adhere to endothelial cells lining the blood vessels) and extravasate by squeezing between the endothelial cells to leave the circulation to reach the site of infection in tissues. This process is known as diapedesis. Adhesion is mediated by receptors on the granulocytes and ligands on the endothelial cells, and is promoted by chemo-attractants (chemokines) such as interleukin-8 (IL-8).
Like monocytes, granulocytes also have pattern recognition receptors, and PMNs play an important role in acute inflammation (usually synergizing with antibodies and complement) in providing protection against microorganisms. Their predominant role is phagocytosis and destruction of pathogens.
The importance of granulocytes is evident from the observation of individuals who have a reduced number of white cells or who have rare genetic defects that prevent polymorph extravasation in response to chemotactic stimuli. These individuals have a markedly increased susceptibility to bacterial and fungal infection.

Question 15

Polymorphonuclear Granulocyte – Neutrophils

Answer 15

Make up over 95% of the circulating granulocytes.
10-20µm in diameter.
Attracted to the following chemotactic agents:
Protein fragments released when complement is activated (C5a)
Factors derived from the fibrinolytic and kinin systems
Products of other leukocytes and platelets
Products of certain bacteria
Neutrophils carry enzymes and antimicrobial proteins stored in two main types of granule:
the primary (azurophilic) granules are lysosomes containing acid hydrolases, myeloperoxidase, and muramidase (lysozyme); they also contain the antimicrobial proteins including defensins, seprocidins, cathelicidins, and bacterial permeability inducing (BPI) protein
the secondary granules (specific to neutrophils) contain lactoferrin and lysozyme.

Express:
CD11a, b, and c -> associated with CD18β2 chains (adhesion molecules)
CD64, CD32, and CD16 -> Fc receptors (bind antibodies)