PCL 5 – ANNA’s OUT OF BREATH

- Link between Asthma, Hayfever and Eczema

o ‘Atopic’ individuals – if you have one your likelihood of having another increases substantially. Similarly, if a family member has an atopic condition, the individual has an increased likelihood of having the condition.
o Atopic disorders are traditionally characterised by a wealing skin reaction
o We know that asthma is an inflammatory condition, the same is true for Hayfever and Eczema. There are several key cells involved in this inflammatory process –
§ Mast cells – increased in the epithelium and release histamine, prostaglandin and leukotrienes à it is this which causes the immediate inflammatory reaction
§ Eosonophils
§ Macrophages and lymphocytes
o Process is not completely known but is associated with –
§ Increased Th2 CD4 lymphocytes in the skin (drive inflammatory process)
§ Increased IgE levels
o Increased IgE levels
§ can be the result of either genetic or environmental factors
§ link between IgE levels and the prevalence of asthma and responsiveness of airways
o Many genes play a key role in asthma development
§ IL-3, IL-4, IL-5, IL-9, IL-13 and GM-CSF affect Mast Cell and Eosinophil levels
o Current suggestion
§ Growing up in a ‘clean’ environment may predispose towards an IgE response to allergens and vice versa
o Intrinsic asthma is IgE related – triggers include allergens from animals, flour and grain, latex
o Atopic individuals develop occupational asthma more rapidly when exposed to agents causing the development of specific IgE antibody
o In asthma the epithelium of the conducting airways is damaged and stressed with loss of ciliated columnar cells onto the lumen. As the epithelium is a major source of mediators, cytokines and growth factors that serve to enhance inflammation à damage to the epithelium makes it more vulnerable to allergens (such as those which cause hayfever)