Metal hypersensitivity (also called metal sensitivity or metal allergy) is a disorder of the immune system that affects 10% to 15% of the population. In susceptible people, exposure to certain metals is followed by a cell-mediated immune reaction (type IV hypersensitivity, also called delayed-type hypersensitivity).

A type IV hypersensitivity reaction is mediated by T-lymphocytes (white blood cells) that have had prior contact with a given allergen. These cells respond by enlarging (lymphoblast transformation) and dividing (proliferation) when exposed to the sensitising allergen. The newly formed effector cells, together with their secreted cytokines, mediate the resulting allergic reaction.

Inflammation activated by metal allergy may be one of the causes of ill health in patients. Type IV metal allergy is often overlooked as a culprit in many of today’s chronic illnesses, more info HERE.

With a skin test or, more objectively and safely, with a lymphocyte transformation test (also referred to as “LTT” or “LPT” test). MELISA is an optimised and validated lymphocyte transformation test.

The classic symptom of metal hypersensitivity is allergic contact dermatitis. In addition to local symptoms, chronic exposure to metals may cause numerous symptoms associated with an overactive immune system in susceptible people. Patients with metal hypersensitivity report symptoms such as inflammation, joint and muscle pain, cognitive impairment (brain fog), depression and headaches. Metal hypersensitivity has been implicated in the aetiology of chronic fatigue syndrome, autoimmune disease, fibromyalgia and multiple chemical sensitivity.

By optimising the methodology of LTT, MELISA has improved both the specificity and the sensitivity of the test. Below are the four major changes that MELISA implements, in contrast with LTT.

1. MELISA uses a higher number of lymphocytes per test

2. The metal concentrations used have been chosen so that they are non-mitogenic and non-toxic

3. The test uses partial depletion of macrophages which restores the lymphocyte-monocyte balance so that it is similar to that in the blood

4. In addition to objective determination of lymphocyte proliferation by radiolabeled thymidine, morphological examination gives an additional reading directly on the level of stimulated lymphocytes

The MELISA test was validated on 250 patients in 2003 and found to be reproducible, sensitive, specific and reliable for detecting metal sensitivity. Further validation on a larger group of patients was published in 2016. In 2021, a university study wrote about the “significant benefits of MELISA testing”.

To our knowledge, no other LTT except the widely published beryllium-LTT has been validated.

The most frequently allergenic metals are nickel, gold, palladium, cadmium, various mercury compounds, cobalt, chromium and molybdenum. Other metals can induce positive responses in MELISA as well. Everyone has a unique immune system and basically, any substance could trigger an immune response in susceptible individuals.