Immune system part 2

Question 1

Immune response: timeline

Answer 1

First barrier: physical and chemical (innate immune response)
Second barrier: cells innate immune response, phagocytic and NK cells (non specific, does not induce memory)
Third barrier: cells acquired immune response (specific, induces immune memory, long lasting immunity)

Question 2

name the cells involved in innate immunity

Answer 2

basophil, eosinophil and neutrophils
mast cells
natural killer cells

Question 3

name the cells involved in adaptive immunity

Answer 3

macrophages and dendritic cells

b cells and t cells

Question 4

how are nt cells activated

Answer 4

Interferon attacks the virus directly and also makes the MHC less efficient
Decrease of MHC I tips NK cells to destroy the infected cell. NK are non specific, they are lymphocyte after all but they do not need priming in the same way that T cells or B cell need.

Question 5

how are macrophages, and neutrophils that phagocyte activated

Answer 5

Virus produces protein that the cells expose in the MHC I and this activates cells from the innate immune response such as macrophages, and neutrophils that phagocyte the infected cell or cause cellular destruction and they phagocyte the “left overs”. These also trigger the activation of maturation of T cells as macrophages are also APC.

Question 6

How are Cytotoxic T cell and helper T cells activated?

Answer 6

Virus produces protein that the cells expose and Cytotoxic T cell attacks the marked cell which are displaying viral proteins with cytokines and other enzymes such as perforins that make holes in the cells, leading to apoptosis (death – self destruction)
When recognized by a CD4+ cell, this cell does not kill the infected cell but activates other pathways such as Bcell activation

Question 7

Innate immune response

Answer 7

Non specific and quick
Physical barriers (skin, mucous membranes)
Chemical barriers (saliva, gastric enzymes, skin gland secretions, tears, flora, mucociliar system in airways, milk, urine, mucus)
Cellular “barrier” made of phagocytic antigen presenting cells (APCs): neutrophils, macrophages, dendritic cells, monocytes, natural killer cells (NK) –> inflammatory response
APCs inform B and T cells to start adaptative (specific, long lasting) immunity
Inflammatory response, including the complement

Question 8

Inflammatory response

Answer 8

Rapid mechanism of response to tissue damage, injury or infection, which ends with healing or death of tissue
Reaction of tissues to an irritant as a hypersensitivity response
Inflammation prevents the spread of infection and speeds up healing, alerts the immune system but it might be detrimental to the animal!!
The signs…
PRISH = pain, redness, immobility, swelling, heat
Made by chemical signalling cascades that lead to the production or involve the production of inflammatory cytokines
Histamine, bradykinin, PG, IL-6, TNF-⍺, IL-1 are some examples of substances that lead to non-specific local (swelling and exudate) or systemic (fever) reactions
Some of these substances also attract cells from the immune system that will phagocyte pathogens and infected cells
A good example is the formation of pus (dead tissues, neutrophils that have phagocyted pathogens and dead pathogens)
Tumour necrosis factor (TNF)
Prostaglandins (PG)
Interleucin (IL)

Question 9

Examples of innate immunity

Answer 9

Dendritic cells in the skin
Mucociliary system in the respiratory system
In GIT, saliva and gastric acids (HCl)
Physical barriers: skin, mucous membranes
Neutrophils and macrophages phagocyting pathogens
Cellular lysis by T cytotoxic cells and NK cells
Complement activation that leads to pathogen lysis

Question 10

Adaptative immune response

Answer 10

Specific, long lasting, slower to kick in and with memory (except colostrum)

Cellular (T cells) and humoural (B cells producing antibodies)
Memory (B memory cells)

Question 11

Adaptative immune response: Active

Answer 11

Cellular and humoral immune responses from immune system
Generates memory, duration of memory variable
Cell mediated Immunity – T cells
. Humoural Immunity – B cells

Question 12

Cell mediated Immunity – T cells

Answer 12

(thymus gland)
T cells when activated will turn into:
Cytotoxic T cells (CD8+)  kills the cell and any cell with the same antigen!
T helpers:
Th1: amplify number of T cells and NK/macrophages
Th2: activate B cells

Question 13

Humoural Immunity – B cells

Answer 13

(antibody production)
B cells would trigger formation of antibodies:
Neutralising the pathogen
Marking it leading to opsonisation (by macrophages)
Activate the complement
B cells could also create “memory” B cells (plasma cells), super creators of antibodies

Question 14

Adaptative response: Passive

Answer 14

Antibodies produced by a mother that are passed to a puppy via colostrum (antibody-rich first milk produced)
Antibodies produced by another animal and given to a sick animal (e.g., administration of tetanus antitoxin)
They do not induce immunity memory
It is essential that neonates receive colostrum within the first 24 hours of life because in some species the intestinal barrier closes at 48h not letting any Ig through! Remember this when doing a C section in dogs and assisting newborns in other species!

Question 15

Artificial” active adaptative immunity

Answer 15

Vaccination
Moderna and Pfizer-BioTech: mRNA
Oxford-AstraZeneca spike protein B dsDNA vaccine
Different “protection”, “efficacy” and preservation conditions

Question 16

Secondary Immune Response

Answer 16

the reaction of the immune system when it contacts an antigen for the second and subsequent times. Responding Cells. B cells and T cells are the responding cells of the primary immune response

Question 17

What types of immune cells are you likely to find in a blood smear?

Answer 17

A lymphocyte is one of the subtypes of a white blood cell in a vertebrate’s immune system. Lymphocytes include natural killer cells (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic adaptive immunity), and B cells (for humoral, antibody-driven adaptive immunity).

Question 18

What are interferons?

Answer 18

a group of signaling proteins made and released by host cells in response to the presence of several viruses.In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their anti-viral defenses.

Question 19

What is an antigen?

Answer 19

a toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.

Question 20

Which cells make antibodies?

Answer 20

Antibodies are produced by specialized white blood cells called B lymphocytes (or B cells ). When an antigen binds to the B-cell surface, it stimulates the B cell to divide and mature into a group of identical cells called a clone. The mature B cells, called plasma cells, secrete millions of antibodies into the bloodstream and lymphatic system.

Question 21

How would you define apoptosis?

Answer 21

the death of cells which occurs as a normal and controlled part of an organism’s growth or development

Question 22

What is humoural immunity and how is it different to cellular immunity?

Answer 22

The difference between humoral and cellular immunity are mainly due to two factors like the type of an immune response and the regulation of immunity. Type of Immune response: Humoral immunity produces an antibody-mediated immune response, whereas cellular immunity produces a cell-mediated immune response
Humoural means fluids, involves antibodies. Cellular involves the immune cells

Question 23

What is a T helper?

Answer 23

The T helper cells (T h cells), also known as CD4 + cells, are a type of T cell that play an important role in the immune system, particularly in the adaptive immune system. They help the activity of other immune cells by releasing T cell

Question 24

How do vaccines work?

Answer 24

How vaccines help Vaccines contain weakened or inactive parts of a particular organism (antigen) that triggers an immune response within the body. Newer vaccines contain the blueprint for producing antigens rather than the antigen itself.

Question 25

components of the humoral response

Answer 25

Triggered by B cells (plasma cells): production of antibodies

Question 26

What antigen presenting cells do you remember?

Answer 26

Dendritic, macrophages and B cells

Question 27

List two examples of innate immunity and two of adaptive immunity

Answer 27

Innate: macrophages, neutrophils, mast cells, natural killer cells, the complement, skin, mucous membranes. And adaptative: plasma cells, production of antibodies, T helper cells, memory cells