objectives and background. objectives to identify the allergic versus the non allergic individual to...
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Objectives and background
Objectives
• To identify the allergic versus the non allergic individual
• To understand the strengths and limitations of conventional and alternative allergy testing
• To select the appropriate management strategy following a relevant history and appropriate testing
Products of the mast cell• Preformed - immediate release
• Histamine• Tryptase• Hydrolases
• Secreted mediators - released a few hours later• Prostaglandins• Leukotrienes• Cytokines
Is allergy becoming more common?
• Selective perception
• ? Previously underestimated
• Increasing worldwide
• Incidence of hayfever and asthma rose in East
Germany following unification
So why are allergies increasing?
• The role of the farm environment in reducing the risk of hayfever and asthma is established.
• Applies only to children in the first year of life and must to be maintained to aged 5.
• The “Farm Effect” may result from the increased exposure to bacterial products such as endotoxin
Endotoxin - LPS - from outer cell membrane of all gram negative bacteria
• Presence of household animals is associated with higher levels of house dust and airbourne endotoxin in metropolitan homes
• Paradoxically the high exposure to cat allergens reduced sensitisation, whereas high HDM increased likelihood of sensitisation.
• Local factors will significantly alter the endotoxin exposure in the home.
• Personal hygiene measures such as fastidiousness of bathing, laundering and floor cleanliness are prime endotoxin reducing candidates
Prevalence of Atopic Eczema
• Urban > Rural
• Small > Large families
• Well off > Poorer households
Genetic influence
• Parental atopy especially maternal
• Concordance for allergy between twins
“Hygiene hypothesis”• ‘Modern living is associated with too little
microbial stimulation early in life’ • ‘Microbial deprivation syndrome’ - cleaner
environment and the widespread use of antibiotics’
• Higher birth order associated with allergies, -‘The Sibling effect’
• Recurrent infections lead to Th1 >>Th2 (multiple rather than a few microbial species)
Probiotics
• ‘Living (or inactivated) organisms that are claimed to exert when ingested beneficial effects on health’ EAACI 2002
• Particularly Lactobacilli, Bifidobacteria, Enterococci and E. Coli
• Meningitis associated with Bifidobacteria• Fatal sepsis with a vancomycin resistant
Lactobacillus• Only preliminary studies available and not
conclusive
Probiotics in primary of atopic disease: a randomised placebo controlled trial
• Lactobacillus GC given 4 weeks prenatally to mothers with > one first degree relative with atopic eczema, allergic rhinitis and asthma and postnatally for 6 months to breastfeeding mothers/their infants
• End point - chronic recurring eczema• Eczema diagnosed in 46/132 (35%)• Frequency of eczema in probiotic group was half that
in placebo group, 15/64 (23%) vs 31/68 (46%) The Lancet 2001; 357:1076-9, follow up 2003;361:1869-71 SPT same