Lecture 10

Question 1

what is the primary job of the immune system ?

Answer 1

Recognize self from nonself.
Nonself = bacteria, virus, parasites and our own cells that have become defective (such as become cancer)

Question 2

3 major functions of immune system

Answer 2

1) recognize and remove abnormal self cells (ex cancerous cells)

2) remove dead or damaged cells + old red cells

3) protect body from disease causing pathogens

Question 3

How do we call substances that trigger the body’s immune response ? And the ones that react with products of the response ?

Answer 3

Immunogens
Antigens

Question 4

what is the first line of defense of the body ? (components)

Answer 4

physical + chemical barrier :
- skin
- mucus (glygoprotein chains+ water)
- stomach acid

Question 5

what are the two anatomical components of the immune system ?

Answer 5

Lymphoid tissues and cells responsible for immune response (mast cell, eosinophil, neutrophil, macrophage, lymphocyte, dendritic cell)

Question 6

structure of the lymphatic system

Answer 6

Primary : thymus (T cells) + bone marrow (cells form and mature)

Secondary : nodes, tonsils, GALT, …

Question 7

what does the bone marrow consist of ? What does it do ?

Answer 7

It consists of blood cells in different stages of development + supporting tissue (stroma).
All the blood + immune cells derive from the same pluripotent stem cells.

Question 8

what cells are antigen presenting ? (3)

Answer 8

macrophages, lyphocytes / plasma cells, dendritic cells

Question 9

innate immune response : what is it, what does it do, type of cells, opsonins ?

Answer 9

Non specific : patrolling cells respond to a broad range of foreign material -> clear the infection or contain it until aquired immune response is activated.

Phagocytes or natural killer cells.

Opsonins : bind to pathogens and make them recognizable for macrophages

Question 10

what happens at the end of phagocytosis ?

Answer 10

The macrophage displays the antigen fragments on surface receptors (antigen presentation) -> activate rest of immune response

Question 11

what are complement proteins ? what do they do ?

Answer 11

Plasma proteins, generated in liver.
They create membrane attack complexes = insert in membrane of pathogen to create pores -> cells swells and dies

Question 12

differences between B and T cells

Answer 12

B = develop in bone marrow, antibody production, immunological memory cells

T = develop in thymus, cytotoxic cells -> defense against intracellular pathogens

Question 13

what happens after an antigen is presented by an APC ? (what happens with B and T)

Answer 13

T helper cells are activated :
- guide cytotoxic T cells to pathogens or infected cells
- activate macrophages
- present antigen to immature B cells -> proliferation of antigen specific B cells -> production of antibodies

Question 14

difference between first and second infection of same pathogen

Answer 14

First response is slow and low concentration of antibodies, but we create B memory cells.

Second response is much faster and much more antibodies.

Question 15

what does it mean clonal expansion ?

Answer 15

B cells will replicate as clones : specific to one antigen, and will this procude antibodies for only that antigen

Question 16

structure of an antibody

Answer 16

two light chains (short) and two heavy chains (long), linked by disulfide bonds.
At the top of the “Y” are the antigen binding sites.
The opposite side can be recognized by macrophages.

Question 17

5 functions of antibodies

Answer 17

1) cause antigen clumping / inactivation of bacterial toxins
2) act as opsonin to tag antigens for phagocytosis
3) trigger degranulation (mast cells)
4) activate complement
5) activate B lymphocytes

Question 18

difference between active and passive immunity

Answer 18

1) active : when body is exposed to pathogen and produces antibody and memory cells (natural or artificial such as vaccines)

2) passive : aquire antibodies from another organism (injections, mother to foetus, …) -> only lasts as long as antibodies are in the body because no memory cells generated