IgE antibodies to foods

IgE (immunoglobulin E) is the antibody class that triggers immediate allergic reactions. Only very small amounts of IgE circulate in the blood, because most of it is firmly bound to immune cells. IgE antibodies to foods are measured in serum – in the test catalogue as part of “Vorscreen B”, together with IgG4 antibodies to foods, pollen-associated food reactions and DAO. The blood sample is taken in a practice. The value differs fundamentally from IgG and IgG4 antibodies to foods, which are explained on their own pages.

What IgE antibodies do in the body

When the immune system comes into contact with a protein that it wrongly classifies as dangerous, B cells produce IgE antibodies against it under the influence of certain helper cells (Th2 cells). These antibodies attach to mast cells in the skin and mucous membranes and to basophil blood cells – this is called sensitisation. On renewed contact, the food protein links neighbouring IgE molecules, and within minutes the cells release histamine, tryptase and other messengers. These widen the blood vessels, make them leakier, contract smooth muscle and irritate nerves.

IgE to foods not detected – what does it mean?

If no IgE to the tested foods is detected, the immune system has not built up a measurable allergic sensitisation to these proteins. An IgE-mediated immediate reaction is therefore less likely. Other reaction pathways are not affected by this: intolerances without involvement of the immune system – for example to lactose, fructose or histamine – and reactions involving other immune cells cannot be captured via IgE. Foods that were not part of the test are not assessed either.

IgE to foods detected – what happens in the body?

A positive result means that mast cells and basophils are loaded with IgE to this food and can react on contact. Typical consequences are tingling and swelling of the lips and mouth, hives, itching, nausea, abdominal cramps or diarrhoea, less often shortness of breath or circulatory reactions. Sensitisation often arises via pollen: antibodies to birch pollen, for example, recognise similar proteins in apple, hazelnut or carrot (cross-reaction). However, sensitisation is not the same as an allergy – some people have IgE to a food and tolerate it without symptoms. The level of the value does not reliably predict the strength of a reaction.

The interpretation is given in your report.