In more complex reactions such as in drug, venom or food allergies,
specific IgE may fail to demonstrate absolute diagnostic reliability.
The solution is the BÜHLMANN complete Cellular Allergy diagnostics package.
Cellular Allergen Stimulation Test
Choose from the CAST ELISA or the Flow CAST whole blood flow cytometry method for Basophil Activation Testing (BAT).
With over 160 standardised allergens including food, food additives, drugs, insect venoms and inhalants they provide complete solutions for allergy testing.
The physical symptoms of allergy can be similar to that of a sensitivity or intolerance. Roughly 20% of the population experience symptoms that make them believe they have a food allergy, but it’s estimated that only 1-10% of adults and children actually have a food allergy. The incidence of food allergies are becoming increasingly more prevalent; it’s estimated that, in the UK, 1 in 40 infants are developing a peanut allergy, and 1 in 20 infants are developing an egg allergy. With almost a third of allergy sufferers having to change their lifestyle, it’s vital to determine who is truly allergic from those who are not; BAT can be a helpful tool to do this.
About 10% of the general population claim to have a penicillin allergy, however fewer than 10% of people who think they are allergic to penicillin are truly allergic. Those with a label of penicillin allergy are more likely to be treated with broad-spectrum antibiotics, and use of broad-spectrum antibiotics is associated with an increased rate of clinical complications, such as antibiotic resistance. An unsubstantiated label of penicillin allergy may lead to the inappropriate use of broad spectrum, non-penicillin antibiotics leading to antibiotic resistance and in some cases sub-optimal therapy.
The general pathway for suspected allergy diagnosis recommends the following:
Firstly, a detailed clinical history of the patient will be taken
Based on the results of the clinical history, a healthcare professional will offer a skin prick test (SPT) and/or a blood test for specific IgE (sIgE). The results of these tests will then be interpreted along with the results of the clinical history
If the results from the SPT and sIgE tests are unable to confirm or exclude allergy conclusively, patients may be referred to specialist or secondary care settings for further investigation (e.g. challenge test)
A Safer Alternative to Challenge Tests
Challenge tests can be unpleasant and stressful for patients and their families, as well as posing a danger to the patient. BAT can be used as a safer alternative to a challenge test if SPT and/or sIgE testing cannot offer a conclusive result- if the patient has a positive BAT result, allergy can be confirmed with a high degree of certainty; if the patient’s BAT result is negative, patients may be offered a challenge test to definitively confirm or exclude allergy.
Offering BAT before a challenge test will significantly reduce the number of patients having to undertake these tests; a peanut study undertaken by Santos et al. in 2014 has shown a 67% reduction in the need for oral food challenges. The true value of BAT lies in its high specificity, reaching 100% in some studies. This means that a positive BAT result confirms allergy with a high degree of certainty, resulting in fewer of the more dangerous positive challenge tests being performed.