Vaccines And Autoimmunity Flashcards
Two types of immunity
Passive
Active
Two types of passive immunity and a brief description
Natural - transfer of maternal antibodies across the placenta to the developing foetus
Artificial - treatment with pooled normal human igG or immunoserum against pathogens or toxins
explain the process of active immunity
- Engage the innate immune system (neutrophils, NK cells, dendritic cells, macrophages)
- Elicit “danger” signals that activate the immune system,
triggers such as molecular fingerprints of infection –PAMPs and engage TLR receptor
3- activate specialist antigen presenting cells
4- engage the adaptive immune system - generate memory t and b cells , activate t helper cells.
Summary of passive immunity
No host participation
Transient and less effective
No lag period
No memory present
No negative phase
Summary of active immunity
Produced by the host immune system
Induced by infection or vaccines
Durable effective protection
Effective after initial lag period
Immunological memory is present
Boosted effect on subsequent dose
Negative phase
3 advantages of active immunity
Induces immunological memory
Produces high affinity antibodies
It produces a persistent protective response against pathogens
2 adv of passive immunity
Immediate effect
Useful treatment for acute dangers
WHAT type of hypersensitivity reactions involve antibody-antigen complexes
type 3
what is primary vaccine failure
person doesnt develop immunity from vaccine
what is secondary vaccine failure
initially responds but protection wanes over time
define hypersensitivity
objectively reproducible symptoms or signs, initiated by exposure to a defined stimulus at a dose tolerated by normal subjects’ and may be caused by immunologic (allergic) and non‐immunologic mechanisms’
type 1 hypersensitivity involves ?
IgE mediated drug hypersensitivity
-prior exposure to the antigen/ drug
ige formed after 1st exposure
ige becomes attached to mast cell oe leucocytes,
re-exposure causes mast cell degranulation and can release histamine
type 2 hypersensitivity involves
Drug or metabolite combines with a protein
Body treats it as foreign protein and forms antibodies (IgG, IgM)
Antibodies combine with the antigen and complement activation damages the cells
type 3 hypersensitivity involves?
Antigen and antibody form large complexes and activate complement
Small blood vessels are damaged or blocked
Leucocytes attracted to the site of reaction release pharmacologically active substances leading to an inflammatory process
type 4 reaction involves?
Antigen specific receptors develop on T-lymphocytes
Subsequent admin, adminstration leads to local or tissue allergic reaction
what must an allergic reaction have
subsequent re- exposure
main feautures of anaphylaxis
Exposure to drug, immediate rapid onset
Rash (absent in 10-20%)
Swelling of lips, face, oedema, central cyanosis
Wheeze / SOB
Hypotension (Anaphylactic shock)
Cardiac Arrest
management of anaphylaxis
Commence basic life support. ABC
Stop the drug if infusion
Adrenaline IM 500micrograms(300mcg epi-pen)
High flow oxygen
IV fluids – aggressive fluid resuscitation
If anaphylactic shock may need IV adrenaline with close monitoring
Antihistamines not first line treatment but can be used for skin symptoms
what does adrenaline do
vasoconstriction- increase BP and coronary perfusion via alpha 1 adrenoreceptors
stimulation of b1 adrenoreceptors positive ionotropic and chronotropic effects on heart
clinical criteria for allergy to drug
Does not correlate with pharmacological properties of the drug
No linear relation with dose (tiny dose can cause severe effects)
Reaction similar to those produced by other allergens
Induction period of primary exposure
Disappearance on cessation
Re-appears on re-exposure
Occurs in a minority of patients on the drug
First line treatment for anaphylaxis
500mcg IM ADRENALINE
