immunology Q&A Flashcards
What invading enemies does the immune system have to fight against?
pathogens (invaders)
What are the main layers of the immune system?
- physical and chemical barriers
- non-specific innate immunity
- specific adaptive immunity
List three important discoveries that helped to identify the importance of the immune system and/or how “immunity” is obtained
- Edward Jenner observed milk-maids that contracted cowpox were resistant to smallpox
- Pasteur created the first vaccine (anti-rabies)
- The concept of humoral immunity was discovered in 1890 by Emil von Behring & who derived “antitoxins” from Tetanus
Describe the epithelial barrier.
The first line of defence, a physical & chemical barrier
one cell thick
separates microbe rich surface form body
What are the difference between innate and adaptive immune system?
innate = non specific immunity, includes first and second line of defense. slower
adaptive = specific immunity, includes t & b cells & antibodies. also dependant on previous exposure to pathogen. faster
-What is the most ancient immune response strategy?
the innate immune system
Define three main characteristics of HSCs (Hematopoietic Stem Cells)
1) all RBC and WBC develop from multipotent HSCs
2) is a rare cell type - self-renewing and multipotent
3) found mainly in bone marrow
What is the primary hematopoietic tissue?
bone marrow
-What are the cell types that originate from HSCs?
myeloid precursor & Lymphoid precursor
What are the differences between monocytes and macrophages?
macrophages are a differentiated monoctye
- increase in size, numbers, complexity, phagocytic activity, etc
- becomes a professional APC
What is the main difference between neutrophils and macrophages?
their lifespan.
neutrophils are short lived yet macrophages are long-lived
What is the main difference between dendritic cells and macrophages?
their role
macrophages = phagocytosis of microorganisms (innate effector cells)
DCs = stimulate T cell activation (induce adaptive immunity)
What is the main difference between Myeloid and Lymphoid cells?
the type of cell that they give rise to are all different
What are the analogies and differences between B cells and T cells?
-both lymphocytes
-B cells produce antibodies
-T cells destroy infected cells
What are the main/primary hematopoietic tissues in adult humans?
bone marrow & thymus
Why is the Thymus important?
it is the site of T and NKT cell maturation
What are the differences between the blood and the lymphatic System?
lymphatic system = drains lymph fluid from extravascular tissues, from capillaries through lymphatic vessel - lymph node - thoracic duct - back into bloodstream
blood system = pumps blood throughout the body
What are the main lymphoid tissues?
primary: thymus and bone marrow
secondary: lymph nodes, spleen, MALT (mucosal-associated lymphoid tissues)
tertiary: CALT (cutaneous-associated lymphoid tissue)
List the main lymphoid secondary tissues and describe their structures and functions.
lymph node: site of generation of T cell response and B cell antibody response to specific antigen
spleen: where immune responses are mounted against antigens in the blood
overall: this is where the antigen is trapped
How do immune cells communicate with each other and with other body cells?
through cytokines
What are cytokines
proteins that communicate among cells of immune system
What are chemokines?
cytokines that attract cells with the appropriate receptors to regions where the chemokine concentration is the highest
In how many ways can cytokines work?
3 ways: endocrine, paracrine, and autocrine action
How many classes of Ig are in vertebrates?
5:
IgG, IgM, IgA, IgE, IgD
What mechanisms ensure the high diversity in Ig?
Somatic hypermutation, somatic recombination, class switch
How many different antibodies can be generated based only on the mechanisms of genomic recombination and class switch?
about 10^18 different antibodies
What is the complement?
set of circulating, inactive proteins that are activated in response to a pathogen
How many route of activation of the complement have been described?
3, classical, mannose-binding lectin mediated and alternative
what is inflammation?
a non-specific reaction to noxious stimuli
How is an inflammatory process generated, and what are the consequences of inflammation?
generated by redness, swelling, pain and heat localized at site of infection
consequences: damage to healthy tissue in lungs and brain tissue
Define PAMPs and PRRs.
PAMP: pathogen-associated molecular pattern
PRR: patten recognition receptors
What are the known differences between innate and adaptive immune recognition of pathogens?
innate: non -specific, not directed against specific pathogen
adaptive: recognizes and destroys based off memory
What are the different TLRs, and what do they recognize?
TLR: Toll like receptor
they recognize PAMPS
How do the PRR signal transduction pathways work?
-PRR recognizes a PAMP, and sends signal to the nucleus
-signal activates transcription factors to turn on genes
What happens after APC cells engulf a pathogen or are activated upon PRR-PAMP interaction?
phagocytose the microbes
Where are T-cells activated?
lymph nodes
(on the surface of APC like DC)
-Describe the T-cells activation process
APC activated by PRR and makes IL-12
costimulation B7-CD28
results in activation and signal transduction -> IL-2 & IL-2R
Where are B-cells activated?
in the lymph node
How are B-cells activated?
co-stimulation via cell surface ligand-receptor pairs and additional help vis cytokines (IL-4) activates b cell
the b cell - t cell interaction
What is the consequence of B-cells activation?
their activity in the germinal center
they undergo clonal expansion
How T cells encounter antigen in the lymph node and get activated
the CD4 binds to class II MHC, the APC activated by PRR will make IL-12, and with costimulation the t cell is activated
How B cells encounter antigen in the lymph node and become plasma cells
the t cell - b cell interaction
activated b cell proliferates and clones become memory or plasma cells
Describe how interferon is made and protects against viral infection
produced by virally infected cells
- they serve as a warning system & prevent viral replication
What are NK cells and where do they originate?
cytotoxic lymphocytes and they originate in the bone marrow as an HSC
Describe the main characteristic of the NK cells receptor
they express a set of activating and inhibiting receptors, these receptors are used to determine whether or not to kill a target cell or not
How do NK cells kill the viruses?
inducing apoptosis by the release of perforins/granzymes at the junction of the two cells
What types of peptides are presented by MHC-I?
Present endogenous & foreign cytosolic antigens on MHC I to CD* T cells
What are the two ways CTL kill target cells?
- Perforin/gramzyme pathways
- Fas/FasL pathways
How are NK cells regulated by inhibitory and activating receptors?
if a cell lacks MHC I and displays a stress protein, an NK cell will activate to destroy the target
Describe the strategy for the diversity of MHC-Iand receptors in the human population and why it exists
-there is such a diversity in MHC molecules b/c of how fast pathogens evolve
-strategy= high polymorphism
How antibodies block viral infections (antibodies protection)
- block attachement
- aggregate for phagocytosis
- activate complement for MAC attack
