|
A MELISA (Memory Lymphocyte Immunostimulation Assay) test is a blood test that detects type IV hypersensitivity to metals, chemicals, environmental toxins and molds from one single blood sample. The test does not measure toxicity – 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. Two articles have concluded that the MELISA test is not useful for diagnosis since a large number of false positive results will be obtained. ==Mechanism== 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 hypersensitivity reaction is mediated by T-lymphocytes (or memory lymphocytes) that have had prior contact with a given allergen. In genetically predisposed individuals, an ongoing everyday exposure to allergens can induce the type-IV hypersensitivity with a resulting allergic reaction. 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 amalgams, then the allergens tested for will be the metals most commonly used in dental amalgams, such as mercury, silver, tin, and copper. If a patient has a suspected contact allergy to nickel then the test can be used to test for nickel allergy. This is especially useful in individuals who have clinical symptoms (contact dermatitis) but a negative patch test. The lymphocyte reaction to such an allergen is measured by two separate technologies: one based on the uptake of a radioactive isotope 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「MELISA」の詳細全文を読む スポンサード リンク
|