Module 5 Flashcards
Immunity
ability to resist infectious diseases
2 Mechanisms mediating resistance
Innate defenses and adaptive defenses
2 innate defenses types
surface barriers and internal defenses
2 adaptive defenses
humoral and cellular immunity
3 barriers of entry of pathogens and eg.
physical - skin, mucus
chemical - acid Ph, enzymes `
biological competition - commensals in gut and skin compete with pathogens
properties of innate immunity
rapid acting
similar response each time
initiates inflammation
Phagocytes
neutrophils, monoctyes and macrophages and dendrite cells
neutrophils
70% of WBC, first cell to migrate to infection site
macrophages
phagocytes resident in tissues. blood precursors are monocytes
Other innate immune cells
Mast cells, basophils, eosinophils and natural killer cells
initiation of inflammation
- leukocytosis
- margination
- diapedesis - cells squeezing out
- chemotaxis
how to innate immune cells recognize pathogens
PAMP’s, which are recognized by PRR
4 responses to PAMP’‘S
- Secretion of cytokines
- recognition of organisms for phagocytosis
- enhanced killing
- maturation of dendritic cells
TLR’s and 2 examples
key pattern recognition receptors (PRR) for PAMP’s expressed by innate immune cells.
eg. LPS and flagellin
where do immune cells develop
bone marrow
where do T cells mature
thymus
Steps in lymphatic system
- blood leaves capillaries and enters tissues
- fluid drains out of tissues into capillaries and vessels
- lymph fluid returns to blood stream via thoracic duct
- lymph nodes are filled with immune cells and act as filters
Acquired immunity cells
Lymphocytes- T and B cells
Function of T and B cells
T - provide cell mediated immunity through Cytotoxic T Lymphocytes (CTL) and Helper T cells
B - Secrete antibody proteins which give humoral immunity
Key feature of acquired immunity
has a specific memory
5 antibody classes
- IgM
- IgG
- IgA
- IgE
- IgD
4 ways antibodies act
- neutralisation - antibody binding to virus can block its entry
- opsonisation to promote phagocytosis
- activation of complement system
- triggering if mast cells to release histamine
B and T cell recognition
B cells recognise small region of whole antigen (epitope)
T cells recognise short peptides of antigen, bound on surface of antigen presenting cell (APC) on an MHC molecule.
2 Consequences of antigen recognition
- Proliferation - colonial expansion
- Differentiation - cells mature effector cell
Different approaches to vaccination
- live attenuated
- inactivated pathogens
- subunit
- toxoid
- live vectored
- mNRA
- DNA
PAMPS vs Antigens
PAMPS -stimulates innate immune response which alerts DC to infection
Antigen- recognised by t cell receptor (signal 1)
Heard Immunity + equation
when enough people are immune, infection runs out of hosts
qc=1-R0
dendritic cells
major APC CELLS Mature and migrate to lymph nodes
MHC cell
display antigen to T cell. highly variable
Activation of T cell requires
- signal 1 - t cell receptor binding MHC to Ag
2. Signal 2 - costimulatory signal
Phases of vaccine development
- pre - clinical
- phase 1 human
- phase 2 human
- phase 3 human
- regulatory review
Public education to anti vax
- accurate information
- vaccine safety explained
- rick benefit analysis
what is both signals needed in any vaccine
PAMPS and Antigens
adjuvant
what vaccines use with purified protein to provide innate immune stimulus formally given by PAMPS .
what does a vaccination do
aims to prime the adaptive immune system to the antigens of a particular microbe so the first infection includes a secondary response.
Critical immunisation threshold
fraction of people who need to be vaccinated to stop a disease circulating
R 0- basic reproductive number
average number of people who will be infected by one infectious persons
Causes of immunodeficiency diseases
Genetic or due to exposure
Examples of immunodeficiency disorders
SCID, AIDS, HIV
Auto Immunity
- failure of tolerance
- system or organ specific
Examples of autoimmune diseases
- Type 1 diabetes
- narcolepsy
- multiple sclerosis
- allergies
Requirement for allergies
- prior sensitisation to allergen - results in production of IgE
- allergen binding to IgE mast cells
- severe response leads to anaphylactic shock
Hygiene hypothesis
birth order and expose to kids affects allergy likelihood
What alters our microbiome
- bottle feeding and caesarian
- antibiotics
- household cleanliness
- indoor / urban lifestyle
- diet and obesity
