IMI1: The components of the immune system and introduction to innate immunity Flashcards
What are the effects of X-linked serve combined immunodeficiency (SCID)
Born without a functional immune system
No: T cells & NK cells and non-functional B-cells
Which types of cells are lymphoid?
T cells, B cells and NK cells
Which type of cells are myeloid cells?
monocytes (precursors to macrophages), mast cells, dendritic cells, neutrophils, basophils and eosinophils
T or F only B cells are mediators of immune memory? Explain your answer
False: Both B and T cells mediate memory, they are produced at the same time as effector cells
Can you survive long without T cells?
No you would die in infancy
What are NK cells?
Large cytotoxic lymphocytes that patrol the blood for virally-infected or damaged cells, which hey are able to recognise despite lacking variable receptors
Which types of microorganisms can cause disease?
- viruses
- bacteria
- fungi
- commensal micro-organisms (if they become out of control or leave natural environment)
- parasites
How does SCID come about?
one single mutation in a chain that makes part of a cytokine receptor complex (γC)
What are cytokines?
small polypeptides that are used as messengers in the immune system. Several cytokines utilise common cytokine receptor γ-chains (γC) and, through these receptors, control essential immune responses that use both common and distinct checkpoints
What does commensal bacteria mean?
good bacteria
including viruses, fungi and archaea
Individuals who develop allergies are thought to..?
Have less diverse microbiomes
How much smaller are viruses then bacteria?
10x
How many m^2 of skin is there on average on a human body?
2
How many m^2 of mucus membrane is there on average on a human body?
400
Describe the mechanical and chemical defence of the skin
M: Longitudinal flow of air or fluid
C: fatty acid, B-defensins, lamellar bodies, cathelicidin
Describe the mechanical and chemical defence of the gut
M: Longitudinal flow of air or fluid
C: Low pH, Enzyme (pepsin), a-defensins (cryptdins), Reglll (lecticidins), Cathelicidin
Describe the mechanical and chemical defence of the lungs
M: Movement of mucus by cilia
C: Pulmonary surfactant and Cathelicidin
Describe the mechanical and chemical defence of the eye/nose/oral cavity
M: Tears and nasal cilia
C: Enzymes in tears and saliva (lysozyme) and histatins, B-defensins
What is the mechanical protection common to all barriers?
Epithelial cells joined by tight junctions
What chemical barrier do skin, gut and lungs have in common?
Cathelicidin
Which barriers have B-defensins as part of the chemical mechanisms?
Skin
Eyes/nose/oral cavity
Which barriers have a-defensins as part of the chemical mechanisms?
Gut
Lungs
What is the common microbiological barrier for skin, gut, lungs and eyes/nose/oral cavity?
The normal microbiota which competes with pathogenic ones
What is the second line of defence against a pathogen
innate immune response
State the typical features of innate immune response
Broad-acting (lacking specificity)
fast-acting and can last for days
Why is the adaptive immune response of only deployed is completely necessary?
It involves an array of new cells and proteins and thus costs much metabolic energy to the body which could be used otherwise in other physiological functions.
Name the organs of the immune system
- Adenoids
- Tonsils
- Thymus
- Bronchial-associated lymphoid tissue (BALT)
- Axillary lymph nodes
- Bone marrow
- Lymph nodes
- Lymphatic vessels
- Appendix
- Spleen
- Peyer’s patch
- Inguinal lymph nodes
What are adenoids?
A pair of mucosa-associated lymphoid organs located inside the nose
Describe the tonsils
Large group of lymphoid cells that are located on each side of the larynx
What matures in the thymus?
T-cells
What is bronchial-associated lymphoid tissue?
lymphoid cells and tissues of the respiratory tract found in bronchi – not usually found in adult humans but it can be found in kids.
Where are axillary lymph nodes located?
arm pit
What happens in the bone marrow?
Platelets, white and red blood cells are formed
B cells are developed
What occurs in the lymph nodes?
Secondary lymphoid tissue found where lymphatic vessels converge and where antigens are presented to lymphocytes
What is the function of the spleen?
secondary lymphoid organ where immune responses to blood-borne pathogens are initiated. It is responsible for the removal of old and damaged red blood cells, for holding some extra blood and recycling iron. It is located on the left behind the stomach (upper left side of the peritoneum).
How is Peyer’s Patch involved in the immune system?
part of the gut-associated lymphoid tissue (GALT) and a site where an adaptive immune response can start; located in the small intestine, particularly the ileum.
Inguinal lymph nodes are located where?
Groin
Describe the appendix and where it is found
Secondary lymphoid tissue found at the beginning of the colon
What are lymphatic vessels?
Akin to blood vessels but they transport lymph instead of blood
What are the first cells pathogens come into contact with if they break through the physical barriers?
Macrophages
What do macrophages recruit?
Neutrophils
What type of cells are neutrophils?
the most abundent type of leukocytes
What are macrophages capable of?
recognising pathogens as well as old and damaged cells, and engulf them in a process known as phagocytosis.
What do PAMPs stand for?
Pathogen-associated molecular patterns
What do DAMPs stand for?
Danger-associated molecular patterns
What are PAMPs?
structural features on pathogens, that are essential to their survival and serve as markers to immune cells
What are DAMPs?
structural features on damaged cells, that are essential to their survival and serve as markers to immune cells
APC cells stands for?
Antigen presenting cell
What are the two types of responses by APC cells?
1) Self: No immune response
2) Non-self response: Immune response mounted
When an APC cell comes into contact with a non-self-cell what happens?
Signal 1 occurs
- MHC + antigen
No immune response results
When an APC cell comes into contact with a non-self-cell what happens?
Signal 1 (MHC + Antigen) Signal 2 (CD80/CD86) Activation of immune response
What does MHC stand for?
Major histocompatibility molecules
What do recognition of PAMPs by PRRs lead to?
The activation of Signal 2 (CD80/CD86)
What do PRRs stand for?
Pattern Recognition Receptors
What was the first PRR discovered?
Toll-Like receptor (TLR4)
What do PRRs control in invertebrates?
The innate arm of the immune system and they can also modulate the adaptive immune response
What may PAMPs include?
Flagellin sugar or lipid structures (not found in vertebrates) nucleic acids (single or double stranded RNA)
Where are PAMPs found?
Present in forms and/or locations that are not usually found in healthy vetebrates
What are PAMPs thought to be involved in?
signalling cascades that recognise DAMPs, when these are released from necrotic cells
What types of structures can PRRs recognise?
Bacteria
Virus
Parasites
Yeast