Lymphocyte Transformation Test (LTT)

The Lymphocyte Transformation Test (LTT) is an exvivo diagnostic tool used to detect delayed-type allergic reactions in which T lymphocytes that have been sensitized by an allergen are transformed and proliferate upon rechallenge. in contact with it The detection of specific memory T lymphocytes is performed using flow cytometry in isolated peripheral blood mononuclear cells of sensitized patients, after stimulation with the allergen in question.

Why should I do a Lymphocyte Transformation Test (LTT)?

• The LTT is a safe ex vivo tool for diagnosing the delayed type of allergic reaction and determining the responsible allergen to which the patient is sensitized, during which the subject undergoes a simple routine blood draw and avoids any risk of allergen exposure.
• The LTT can be used alone or in combination with another test (skin tests, challenge tests) to confirm the allergy or as part of the differential diagnosis made by the responsible physician.
• LTT can also help to diagnose delayed-type allergies to drugs, metals, but also to monitor treatment with immunomodulators and the proper functioning of the immune system (detection of immunodeficiencies and functional abnormalities of the cellular immune system).

LTT Technical Characteristics

Mononuclear cells are isolated from the examinee’s whole blood, which are then incubated in vitro in a culture medium with the allergen solution in question and corresponding controls (controls) for 4 to 6 days. Then the presence of activated memory T lymphocytes in the sensitized patients is determined by the laboratory technique of flow cytometry

Flow cytometry ensures:

1. High sensitivity – More reliable results
2. High specificity – Avoid false positive and negative results
3. It is biologically friendly to the environment (radioactive isotopes are not used as in older protocols of the examination)
4. A more complete diagnostic picture for the patient

Symptoms in slow-type allergies may appear hours or even days after contact with the suspected allergen.

Patients to be tested should have previously presented at least two of the following clinical and laboratory features.

1. Positive skin test or challenge test
2. eosinophilia
3. Maculopapular rash
4. Generalized swelling and inflammation
5. Fever
6. Angioedema
7. Urticaria
8. Lymphadenopathy

Where else does LTT apply?:

LTT can be used to diagnose all delayed-type allergic reactions. More specifically, it is a tool for:

1. The detection/exclusion of allergic sensitization to all categories of drugs, such as for example β-lactam and non-β-lactam antibiotics, pyrazolones, contrast agents, non-steroidal anti-inflammatory drugs, etc.
2. The diagnosis of delayed-type allergy to the excipients of the vaccines against Covid
3. The diagnosis of allergies to the metals used as alloys in implants and grafts in dentistry, orthopedics and cardiac surgery. Such metals include nickel, titanium, cobalt, chromium, etc
4. The diagnosis of delayed-type allergic reactions to metals that we come into contact with in our daily lives, either through jewelry and accessories, or through contact with them in the environment and through food.

LTT can be used additionally for thedetection of deficiencies and functional damage of the immune system. The basic principle of the test involves stimulating lymphocytes by exposing them to components of common pathogens or vaccines, so that those antigens with which the patient has been in contact in the past and has acquired specific memory T lymphocytes against them, induce a strong immune response in those whose immune system is working normally.

LTT in Grafts and Implants

LTT can be used to diagnose delayed-type allergic reactions to metals.

More specific:

1. The diagnosis of allergies to the metals used as alloys in implants and grafts in dentistry, orthopedics and cardiac surgery – interventional cardiology. Such metals include nickel, titanium, cobalt, chromium, etc.
2. The diagnosis of delayed-type allergic reactions to metals with which we come into daily contact with them, through jewelry and accessories or from the environment and through food.

Orthopedic/Orthodontic Implant Allergy Symptoms (Delayed Type Allergy)

Hypersensitivity to metals can appear as a skin rash or hives on the skin where the metal comes into contact. When the exposure comes from an orthopedic or orthodontic implant, hypersensitivity may present with numerous symptoms, related to an overactive immune system, including:

• inflammation and pain,
• chronic fatigue,
• joint and muscle pain,
• fibromyalgias,
• apparent recurrent infections around the surgical site,
• headaches
• skin rashes.

Hypersensitivity to metals used as grafts/implants:

The human body is an inhospitable environment for an implanted metal alloy as it is a highly oxygenated electrolyte with a pH of about 7.4 and a temperature of 37°C. This means that all the metals in the implants will be subject to corrosion within the body, releasing metal ions, which can interfere with normal functions. The LTT test can be used in two ways in patients undergoing orthopedic/orthodontic surgery:

1. Prior to surgery, patients whose clinical history indicates metal sensitivity may be prescreened to confirm that they are receiving the most appropriate implant.
2. After surgery, the LTT can be used to identify whether metal hypersensitivity is responsible for any of the symptoms that have developed.

LTT applications in various specialties

1. Orthopaidikí: Orthopaedics: As the number of joint replacement procedures increases, so does the rate of hypersensitivity reactions to implants. For this reason, their timely diagnosis is considered necessary both by implant manufacturers and by surgeons. It is not yet known whether implant failure is caused by metal allergy or whether metal allergy is caused by sensitization due to ion release from problematic endoprosthetic implants. However, it is generally accepted that hypersensitivity testing should be performed in patients with a suspected or documented history of metal allergy. The most general mechanism of metal hypersensitivity is based on the fact that orthopedic implants release metal ions through different types of corrosion, which bind to the body’s enzymes and cellular proteins and may be responsible for unwanted immunological actions as they act as haptens. Delayed-type hypersensitivity (type IV), which is mediated by T-lymphocytes, is the most common type of metal hypersensitivity. The alloys of which the implants are made include metals such as chromium, cobalt, nickel, molybdenum, titanium, manganese, etc.
2. Dentistry/Orthodontics: In sensitized individuals, exposure to metal ions released from dental fillings, crowns, inlays, orthodontic abutments, and titanium implants may induce an immune response that will persist until the source of exposure is removed. Usually dentists focus on problems located in the oral cavity, however patients with metal allergy can present with a wide range of symptoms including chronic inflammation, fatigue, joint and muscle pain, and skin rashes. Most of the metals used in dental restorations such as titanium, chromium, nickel, gold and mercury are transition metals. As their name suggests, they are unstable and their ions can bind to enzymes and cellular proteins in the body. Η πλειοψηφία των ανθρώπων που υποβάλλονται σε κάποια οδοντιατρική επέμβαση, δεν θα αντιδράσουν. However, in sensitized patients, the new structure will trigger an immune response that could lead to allergy and autoimmunity.
3. Cardiac Surgery – Interventional Cardiology / Prostheses (Stents) – Pacemakers – Coils ( Coils): Metals used as material for the construction of stents, pacemakers, as well as other implants in cardiac surgery, have been shown to cause a variety of hypersensitivity reactions similar to the other two cases.
4. Other Applies :

Nickel is the most commonly used metal in our everyday life. It is found in accessories, jewelry and cosmetics, coins, household utensils such as pots, pans and cutlery, as well as in food (e.g. cocoa, chocolate, broccoli, nuts, preserves, etc.) Another commonly used metal, titanium, can be found in toothpaste, processed foods, cosmetics, sunscreens, jewelry, and the coating of some drugs and vitamins. In addition, in our daily life we ​​may come into contact with mercury, which is used in fluorescent lamps, thermometers and thermostats and can be found in contaminated vegetables, fruits and seafood.

It is worth noting that it is important to consider total metal exposure when screening for hypersensitivity. Although symptoms may occur when, for example, an implant is placed, it is possible that the reaction is more complex and that the new implant contributes to a hypersensitivity reaction to metals that were previously tolerated at lower levels, such as through food or external contact.

Metals in Medicine that can be detected by LTT:

What is the procedure required of the patient for LTT?

LTT is a relatively simple procedure for the patient since only one blood draw needs to be done. The only thing the patient needs to pay attention to is:

1. Not have been sick in the last 3 weeks
2. No oral or inhaled cortisone in the last week and no antihistamines for 72 hours
3. They must not be experiencing an exacerbation of allergic symptoms and 2-3 weeks have passed since any allergic reaction.

In detail, the categories of drugs that we can examine if they cause slow-type allergic reactions are:

See in detail the substances for which LTT can be performed for Slow-type allergic reactions here.

*for any substance you wish to test, even if it is not listed above, you can call us to enquire if our lab can carry out the test.