Post on 09-Mar-2018
transcript
Everything you ever wanted to know about bee stings - but were too afraid
to ask
Jean-Pierre Scheerlinck
Ouch, what’s next?
Symptoms of allergic reaction
• Mild symptoms• Swelling• Redness• Pain
• Moderate symptoms• Hives (itchy pustules at other
locations)
• Severe symptoms• Difficulties breathing• Shock• Death
Hives
wikimedia.org
Allergic reaction of the skin
• Symptoms not at the site of sting
• Swelling > edema• Redness > vasodilation• Itchy > palm of the hand
• Can last days – weeks
wikimedia.org
The immune system was not designed for allergic
reactions Immune system is there to fight the bad
guys Viruses , parasites, bacteria, fungi and
cancer
We are not designed to fight bee stings!
Key requirement for immune system Discriminate pathogens (non self) vs self
Appropriate response to pathogens
Do it better the second time round
How do you destroy something much larger than you?
Mast cells Specialised “suicide bombers”
Loaded with “explosives”
Triggered when they receive the right signal
Release many potent molecules
These are the ones responsible for allergic reactions to bee stings
Kuby 2003
How the immune system deals with large parasite
Introducing the cast:“Attack by the suicide
bomber” T cells – The masterminds
Tell B cells what to make
B cells – The bomb makers The make antibodies
Antibodies are specific for foreign material (including bee venom)
Mast cells – The suicide bombers Loaded with toxic products
Covered with antibodies made by B cells
Explode when trigger is present
Adapted from slideworld.org and Kuby 2007
The masterminds
The bomb makers
The suicide bombers
T cells – The masterminds
Antigen
MHC II
Dendritic cell
T helper cell
TCR
CD4
CD4 CD4
Th1 Th2 IFN- IL-4
--
Different types of T cells Hold the balance of power
Affects what the B cells make
Who decides what T cells make? Genetic predisposition Amount of venom present Frequency of exposure
B cells make antibodies
Kuby 2007
B cells make antibodies There are different
antibodies for different functions
IgE is the main trigger
Antibodies compete for binding to toxins
Who decides whether IgE is made? T cells – the
masterminds
Janeway 2001
Mast Cell – The suicide bomber
Molecules Released by Activated Mast Cells
Janeway 2001
Action of Mast Cells at Different Sites
Janeway 2001
Histamine
Mellitin
Phospholipase A
Histamine
Why you need several exposures
Bee venom
bee venom IgE
Why is not everyone affected in same way?
Everyone has mast cells
• Mast cell density does not vary much in time and between people
Presence of IgE varies a lot
• Need exposure to bee venom at least 2 x• Different people have different susceptibilities
Presence of IgE varies a lot
• Repeated exposure leads to formation of other classes of antibodies
• This protects the beekeeper who is stung repetitively• This is the basis for desensitization
• Unusual contact with of bee venom can lead to IgE formation • Beekeepers family exposed through clothing can develop IgE
response
Multiple beestings are dangerous even in non-allergic
people Bee venom composition (63 components)
Mellitin (50% of dry weight) destroys blood cells lowers blood pressure induces release of histamine main cause of pain induces release of cortisol (natural steroid)
Phospholipase A (12% of dry weight) enzyme that destroys cells
Histamine (0.9% of dry weight) same as released by the mast cells causes itchy and pain
ivegothives.com
newsimg.bbc.co.uk
Evolution of reaction to sting
i1.cpcache.com
Beginner beekeeper
• IgG response likely to be low > no neutralisation• Bee sting hurts more than just the sting• Wears full protective equipment
Experienced beekeeper
• Could have developed strong IgG response > neutralisation of bee venom
• Bee sting is same as needle prick without effect of toxin
• Often does not wear gloves
High level of IgG protects against allergy
Beginner: Low levels of IgG
Degranulation
Experienced: High levels of IgG
No degranulation
Responses in experienced beekeeper
After many beestings over prolonged period of time
• Immune response develops more IgE > anaphylaxis• Immune response develops more IgG > non-allergic > most likely
outcome
Implications of presence of high level of IgG
• Neutralises bee venom toxins soon after sting• Very little local reaction > working without gloves!• Even if stung many time, beekeeper is unaffected• Regular beestings keeps IgG antibody levels high
Beekeeper retires
• Very few beestings > IgG levels drop• No neutralisation of bee venom• Possibility of IgE response developing > Allergic reaction
PeerJ 2:e338;DOI 10.7717/peerj.338
Removing the stinger without injecting the venom
prbka.co.uk
Anaphylactic shock - treatment
askdoctork.com
What to do? Prevent more stinging Remove stinger to minimise
amount of venom Apply ice to reduce swelling (20
min) Anti-sting medication (“Stingo”) Anti-histamine If anaphylactic Epi-pen >
emergency
Infrequent < 5% of population
Symptoms > Immediate type hypersensitivity Neurological Respiration Heart
If stung 10X or more on face > emergency even if not allergic(unless regular reactionless stings > very high levels of IgG)
Treatment and prevention of allergic responses
Treatment Anti-histamine
Blocks histamine effect on smooth muscle and blood vessels
Epi-pen (Adrenaline/epinephrine ) Increase blood pressure and cardiac output Inhibits mast cell degranulation
Prevention Desensitisation (repeated injection of small doses of venom)
Danger: Do not try this on your own !
IgG up and IgE down > Move from “beginner” to “experienced” beekeeper
Induces tolerance (?)
The end
montybees.org.uk
depi.vic.gov.au
Bee pest and disease training opportunity
Are you: Interested in learning about bee pest and disease?
Committed to completing an online course?
A good communicator willing to share your knowledge?
Apicultural Industry Advisory Committee will fund: Online course from TOCAL college in NSW: “Pests and diseases of honey bees”
Time commitment: 25h
Value: ~$415 reimbursement of online course fee upon: Successful completion of all course requirements
Delivery of 3 communications to other beekeepers including one formal presentation
Additional information: Club needs to nominate 1 person
Managed by B Cooper and J-P Scheerlinck through VAA Melbourne section
Expect more information via club officials