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