- MELISA
A MELISA (Memory
Lymphocyte ImmunostimulationAssay ) test is ablood test that detects Type-IVallergy tometal s,chemical s, environmental toxins andmold s from one singleblood sample . It can also identify activeLyme disease (Lyme Borreliosis). The test does not measuretoxicity -that is to say, it will not measure the amounts of a harmful substance in the patient's blood. It measures if the patient is allergic to it.How the MELISA test works
A MELISA test measures a so-called Type-IV delayed hypersensitivity reaction. In contrast to a Type-I allergy, which is mediated by IgE antibodies and is often tested using an
ELISA test, a Type-IV allergic reaction is mediated byT-lymphocyte s (or memory lymphocytes) that have had prior contact with a givenallergen . [Stejskal VDM, M Forsbeck, R Nilsson. Lymphocyte transformationtest for diagnosis of isothiazalinone allergy in man. J Invest Dermatol 1990; 94:798–802.] In genetically predisposed individuals, an ongoing everyday exposure to allergens can induce the Type-IV hypersensitivity with a resulting allergic reaction [Willis CM, E Young, DR Brandon, JD Wilkinson. Immunopathological and ultrastructural fi ndings in human allergic and irritant contact dermatitis. Br J Dermatol 1986; 15:305–316.] .The test procedure is a cell culture and requires live memory lymphocytes. Lymphocytes are isolated and cultured in an incubator for five days. A portion of the blood is kept intact (unexposed to allergens) to serve as a negative control. A second portion is exposed to a universal allergen, such as
Pokeweed , to serve as a positive control. Finally, the third portion of the blood is exposed to the suspected allergen in several different concentrations, to ensure that the conditions in vitro are as similar as possible to the ones in vivo.As an example, if a patient has a suspected allergy to dental
amalgam s, then the allergens tested for will be the metals most commonly used in dental amalgams, such as mercury,silver ,tin ,copper and so on [Silvennoinen-Kassinen S, A Niinimäki. Gold sensitivity blasttransformation. Contact Derm 1984; 11:156–158.] [Stejskal VDM, M Forsbeck, KE Cederbrant, O Asteman. Mercury-specific lymphocytes: an indication of mercury allergy in man. J Clin Immunol 1996; 16:31–40.] [Marcusson JA. Contact allergies to nickel sulfate, gold sodium thiosulfate and palladium chloride in patients claiming sideeffects from dental alloy components. Contact Derm 1996; 34:320–323.] . If a patient has a suspected contact allergy to nickel then the test can be used to test for nickel allergy [Everness KM, DJ Gawkrodger, PA Botham, JAA Hunter. The discrimination between nickel-sensitive and non-nickel-sensitive subjects by an in vitro lymphocyte transformation test. Brit J Dermatol 1990; 122:293–298.] . This is especially useful in individuals who have clinical symptoms (contact dermatitis) but a negative patch test [Klas PA, G Corey, FJ Storrs, SC Chan, JM Hanfi n. Allergic and irritant patch test reactions and atopic disease. Contact Derm 1996; 4:121–124.] [Rietschel RL. Reproducibility of patch-test results. Lancet 1996; 347:1202.] . The lymphocyte reaction to such an allergen is measured by two separate technologies: one based on the uptake of a radioactiveisotope by dividing lymphocytes (proliferation); the other by classical microscopy evaluation (transformation). The level of reactivity is measured as a Stimulation Index (SI), against the naïve lymphocytes from the unexposed sample (negative control). Viability and reactivity is determined by cell count as well as reaction to the positive control [Sachs B, H Merk. Demonstration and characterization of drug-specific lymphocyte reactivity in drug allergies. ACI International 2001; 13:91–98.] [Stejskal VDM, K Cederbrant, A Lindvall, M Forsbeck. MELISA – an in vitro tool for the study of metal allergy. Toxicol In Vitro 1994; 8:991–1000.] .How the MELISA test is used
Occupational medicine
The MELISA test is used in
occupational medicine and environmental health. It has been used to screen workers exposed to metals, chemicals or other allergens in their workplace. This is what the test was developed for originally, at the Astra (now Astra-Zeneca) laboratories inStockholm ,Sweden . In the U.S., a similar technique (LTT) is routinely used to screen forBeryllium allergy in asymptomatic workers exposed to Beryllium dust [Mroz MM, K Kreiss, DC Lezotte, PA Campbell, LS Newman. Reexamination of the blood lymphocyte transformation test in the diagnosis of chronic beryllium disease. J Allergy Clin Immunol 1991; 88:54–60.] [Newman LS. Signifi cance of the blood beryllium lymphocyteproliferation test. Environment Health Perspect (Suppl 5) 1996; 104:953–956.] . Other occupations that use sensitivity testing include construction work,mining , electrical work, rubber/wood/ paper/textile industry work,dentistry , hairdressing, and painting [Bach FH, K Hirschhorn. Lymphocyte interaction: a potential histocompatibility test in vitro. Science 1964; 143:813–814.] . The MELISA test is used to screen, diagnose and monitor the immune response of susceptible or affected individuals. It also helps patients suffering fromMultiple Chemical Sensitivity orSick Building Syndrome identify what causes their reactions.Dentistry
In Europe, the test is commonly used in
dentistry to test for allergy todental restorative materials , braces and prostheses [Stejskal VDM, K Cederbrant, A Lindvall, M Forsbeck. MELISA – an in vitro tool for the study of metal allergy. Toxicol In Vitro 1994; 8:991–1000.] . Mucosal changes such as oral lichen, or persistent “cold sores” may be due to an allergic reaction to the metal content in amalgam fillings or dental implants [Stejskal VDM, Olin RG, Forsbeck M. The lymphocyte transformation test for diagnosis of drug-induced occupational allergy. J Allergy Clin Immunol 1986; 77:411–426.] . In a sensitive patient, replacement with non-metallic materials, such as zirconium or ceramics, often leads to disappearance of symptoms. Symptoms may not always be local but can be systemic and include inflammation in different body partsFact|date=June 2008. Metals are potential allergens because their ions bind to cellular proteins (enzymes, surface antigens). Research suggests that this can alter the activity of these enzymes or the presentation of these antigens and induce systemic symptoms characteristic of allergic reactions or autoimmune diseases.urgery and orthopedics
In
surgery ororthopedics , the MELISA test is used to identify an existing allergy prior to surgery or diagnose a suspected one afterwards. Since implants come in many varieties, it is possible to test several metal panels and choose the implant that is best compatible with the patient. This applies to hip joints, kneeprosthesis , screws,pacemaker s, cochlear implants, cervical spine plates and dental implants. In the majority of patients, these implants are biocompatible and cause no symptoms at all. On the contrary, they save lives, alleviate symptoms and often dramatically increase the quality of life. However, in genetically predisposed patients (recent research suggests between 5-10% of all patients, depending on ethnicity and previous exposure), the implants may induce side effects such as pain, dermatitis, swelling, impaired wound healing, aseptic bone infections, and implant loosening [http://www3.interscience.wiley.com/cgi-bin/abstract/110438341/ABSTRACT] . Apart from mercury andberyllium , research has also identifiednickel [Regland B, O Zachrisson, V Stejskal, C-G Gottfries. Nickel allergy is found in a majority of women with chronic fatigue syndrome and muscle pain – and may be triggered by cigarette smoke and dietary nickel intake. J Chronic Fatigue Syndrome 2001; 8:57–65.] ,cobalt ,aluminium , andchromium [Räsänen L, H Sainio, M Lehlo, T Reunala. Lymphocyte proliferation test as a diagnostic aid in chromiun contact sensitivity. Contact Derm 1991; 25:25–29.] as known metal allergens. In rare cases, allergy toniobium ,molybdenum , andcopper has also been seen.Titanium
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