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Science of EPD
Enzyme potentiated desensitisation (EPD) utilises a low dose of mixed allergens together with the enzyme beta glucuronidase and an activator (1-3 diol: a type of alcohol) to exploit a natural mechanism in the body with the aim of desensitising the patient to particular allergens (or antigens).
Beta glucuronidase is an enzyme found in all human tissues. It has several roles in the immune system, some of which vary according to the pH (or acidity level). In normal circumstances it is thought to be a significant up-regulator of the lymphocyte immune response. (Lymphocytes are particular white blood cells which are an important part of our immune system).
An allergic reaction is basically an over-reaction of the immune system to a usually harmless substance. The aim of EPD treatment is to ‘switch off’ this allergic response through the formation or tolerance or suppressor lymphocytes. EPD is considered to be a cell-mediated type of immunotherapy.
The EPD injection is given intra-dermally (superficially into the skin) in order to deliver the EPD dose to the Langerhans and dendritic cells. These cells detect allergens/antigens in the skin, process them, and eventually present them to receptors on T lymphocytes in the lymph glands. These cells also carry information which influences whether these lymphocytes mature into Th1, Th2 or suppressor cells (different lymphocytes, with different effects). The beta glucuronidase, together with the activator and the correct dose of allergens, encourages a tolerance response from the T lymphocytes, leading to tolerance to the allergens. After the first few EPD treatments, the affect of EPD often fades away after 3 to 4 months, as the suppressor T lymphocytes have a 3 to 4 month half life. However, when treatment is well established, the response usually becomes more long term. This is why EPD needs to be given as a course of treatment, with booster doses being needed for a few years in most cases.
There are 2 doses of allergen which promote desensitisation, and these 2 doses are used as appropriate for different patients and conditions. It is important for patients to avoid their allergens after EPD, in order that the environmental/food dose does not add to the EPD dose significantly, leading to failure of treatment, or theoretically to new allergy sensitisation. Whilst some patients respond to the first dose of EPD (particularly in hay fever), others may need several doses before a response is seen. As it takes time for the T lymphocyte suppressor cells to mature, the true response to a dose of EPD is not known until after about 24 days.
The evidence
The largest study of EPD was an audit of 10,372 patients in the USA between 1993 and 2000. Only 3 patients reported possible complications, with none of these being life threatening. Overall, 20% of patients reported an excellent improvement, 30% very good, 26% good, 14% fair, 8% no change and 2% worse. The full paper can be viewed at the Friends of EPD website.
There are quite number of studies into EPD. A review by Dr Len McEwan examines this treatment and much of its supporting scientific evidence. This is available as a downloadable pdf on the attachments menu on this page.