TYPE IV allergy

Delayed-type allergy – primarily significant for adults

Non-IgE-mediated food allergies occur more often for adults in particular. These are based not on IgE antibodies but on allergen-specific T lymphocytes that are directed against food proteins. The symptoms often do not develop until 24 to 48 hours after consuming the food and are therefore difficult to ascribe to what the patient has eaten. Symptoms are also complex. Gastrointestinal inflammatory symptoms are typical (leaky gut), as is eczema, and the intensification of myalgic and arthritic symptoms.

T cell sensitisation to a food can be detected with the lymphocyte transformation test (LTT).
The lymphocyte transformation test (LTT) as a tool in the diagnosis of type IV sensitisation to food is an established and validated procedure in laboratory diagnostics. The use of the LTT to test for food proteins became possible with the utilisation of LPS-cleaned allergens and methodological changes to the LTT which increased its specificity and sensitivity..

In our information brochure "The lymphocyte transformation test", you will find a detailed description of the method used in the LTT. This brochure is available in both German and English, and you can order it free of charge by calling tel. +49 (0)30 77 001-220 or by sending an email to si.service@imd-berlin.de.

The LTT is used in the case of food intolerances when:

  • The reaction does not occur until some hours later and lasts for several days.
  • Eczematous skin changes, gastrointestinal symptoms, myalgia and arthritic symptoms are the main complaints.

Beforehand, subject to the medical history, non-allergic food intolerances such as coeliac disease, lactose intolerance, and histamine intolerance should be ruled out on the basis of the clinical symptoms or via laboratory diagnostics.

There are two test profiles available:

  • LTT TOP 25 foods or
  • LTT Food screen 75
Content of the food test groups in the LTT food screen
pork, chicken, beef, turkey, mutton (lamb), goose, duck
trout, eel, halibut, salmon, cod, carp, tuna, herring
lobster, shrimp, crayfish, sole
wheat, barley, rye, oat, rice, spelt, soy, corn
Brain food
black tea, hops, cocoa beans, coffee beans, brewer's yeast
α-lactalbumine, casein, β-lactoglobulin, BSA (bovine serum albumin)
peanut, walnut, hazelnut, Brazil nut, pistachio, almond, cashew nut
Garden fruits
apple, pear, strawberry, peach, grapes
Citrus fruits
orange, grapefruit, lemon, pineapple, mandarin, avocado, kiwi fruit, banana
garlic, coriander, paprika, pepper, vanilla, cinnamon, aniseed
pea, carrot, potato, cauliflower, celery, asparagus, spinach, tomato, onion
Chicken's egg
egg yolk, egg white
baker’s yeast
as a metal ion present in many foods

The advantage of the LTT food screen 75 is that, with the foods tested, it covers approximately 98% of all known type IV food intolerances. A disadvantage is that the testing in this screening test is performed in groups (e.g. cereals, nuts, etc.) and a positive result for one group needs a follow-up testing to specify the single allergens of that group. This requires a second blood collection.

The systemic nickel allergy – a special form of the "food allergy"

In Germany, approximately 17% of women and 8% of men have a type IV allergy to nickel. 20-30% of these patients react not only to contact with the skin (contact allergy to nickel) – they also react to nickel from food, which is absorbed via the intestine. Studies provide evidence of intensification of the symptoms for atopic dermatitis, eczema, urticaria, and also chronic inflammatory diseases such as rheumatism, other autoimmune diseases, and chronic fatigue syndrome (CFS).
In the case of a known allergy to nickel, the LTT should be used to evaluate whether there is also a systemic sensitisation. Where the result is positive, a nickel-reduced diet should be tried. On this account, nickel is included in the profile for the LTT food screen 75. However, this issue can also be investigated in the individual testing. 

What material is required from the patient?

LTT food screen 75: 20 ml heparin blood and 5 ml whole blood
If follow-up testing of positive food groups is necessary, 20 ml heparin blood per group and one sample of 5 ml whole blood is required.
LTT TOP 25 foods: 30 ml heparin blood and 5 ml whole blood
LTT for nickel (individual): 10 ml heparin blood and 5 ml whole blood

Please request the appropriate collection materials (LTT blood collection sets) from the laboratory free of charge. The blood must be stored in an unchilled environment and reach the lab within 24 hours. Please use our nationwide courier service.


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