delayed skin allergy

A skin test is performed on the patient with various allergens to determine whether the subject is allergic to an allergen to explore and clarify the cause. In addition, a skin test can be performed after immunization with an antigen to examine the subject's ability to respond to an antigen-specific cellular immune response. These tests can only be qualitative and cannot be quantified. Basic Information Specialist classification: skin examination classification: immune examination Applicable gender: whether men and women apply fasting: not fasting Analysis results: Below normal: Normal value: no Above normal: negative: normal. Positive: Indicates that there may be a tuberculosis infection. Tips: Try to avoid experimenting in the hot summer, because the high temperature affects local heat dissipation, can produce non-specific stimulation. Normal value The results were observed at 24, 48, and 72 h, respectively. Positive reaction: ± Suspicious itching or mild redness. + weak positive simple erythema, itching. ++ medium positive red swelling patch. +++ Strong positive redness, papules and blisters. ++++ strong positive redness, blisters, necrosis. Clinical significance (1) Raise: 1OT, PPD tuberculosis, strong positive. 2SK-SD, DNCB, PHA strong positive for T lymphocyte function is normal. (2) Lower: 1OT, PPD miliary tuberculosis when the reaction is weakened, may also be negative. When a healthy person who is not infected with tuberculosis is vaccinated with BCG, both positive and negative are normal. Malignant tumors, leukemia, viral infectious diseases, deficient cellular immune function defects (T cell system) such as over 70 years old, autoimmune diseases, tuberculosis, and other diseases are weakened. 2SK-SD, DNCB, KLH, PHA congenital cellular immune deficiency syndrome (T cell system) is usually negative. When malignant tumors, leukemias, autoimmune diseases, connective tissue diseases, etc. occur in the defect of acquired cellular immune function (T cell system), when these skin reactions are weakened, and sarcoma-like cell-free immune deficiency syndrome, these skin reactions are all weakened to many. Precautions (1) Once a strong reaction occurs during the test, the reagent should be removed and treated accordingly. The principle of treatment is the same as contact dermatitis. If there is erosion, the exudate should be wet, and the redness should be applied daily for many times. Oral corticosteroids. (2) The reagent should be pure and free of impurities. (3) The concentration of the reagent should be non-irritating, but should not be too low. (4) It is not advisable to conduct an experiment during an acute episode of dermatitis. (5) Those who are allergic to tape should avoid using it. (6) Chemically similar reagents can produce cross-allergy, but the response is generally weaker than the original sensitizer. (7) Corticosteroids or other immunosuppressive agents should be discontinued 3 days before the test. (8) Try to avoid experimenting in the hot summer, because the high temperature affects the local heat dissipation, which can produce non-specific stimulating effects. Spot patch test: Some substances are converted into allergens after absorbing light waves in human skin, which in turn causes delayed type hypersensitivity reaction, which is photocontact allergy. This patient does not respond to exposure to the allergen alone. The patient is exposed to the allergen before the test, and then the exposure will produce a positive reaction. This is the spot patch test. The method is to do the three patch tests on the same allergen, followed by black cloth or black paper, respectively indicating the serial number I, II, III, observe the No. 1 result after 48h, and let the exposure for 30 minutes on the II (using 320 ~450nm wavelength ultraviolet light, the light source can also be natural light, Wood lamp, Kromayer lamp, xenon arc lamp, carbon arc lamp, "black light", etc., continue to cover gauze or black paper. Observations II and III were made after 96 hours. As a result, the I and III were positive (that is, the 48h and 96h controls were negative), and only the I showed erythema, edema or blisters as positive for the patch test. Inspection process (1) intradermal injection method: The results were observed 24 to 48 hours after the injection, and the diameters of the blush and the induration were measured. The induration diameter was ≥ 5 mm, and if the induration was small, it may be a cross reaction. If there is redness and swelling in 4~18h, there may be a rapid hypersensitivity reaction. (2) Patch test: The patch test is the standard method for diagnosing contact dermatitis. The test site is often selected for the skin on the back, arms and legs. 1 According to the medical history and clinical observation, suspicious sensitizers are selected and formulated into appropriate concentrations for use. 2 Take 1cm2 large four-layer gauze fullness test solution, apply it on the normal skin of the forearm flexion or back of the subject, cover with 1.5cm2 square or round non-ventilated cellophane or wax paper, and then use a little larger The tape is fixed. The powder is applied to the gauze soaked with physiological saline and applied to the surface of the skin in the same manner. 3 If multiple reagents need to be measured at the same time, the distance between the application points should be at least 4 cm, and each test mark is clear. Not suitable for the crowd There are no taboos. Adverse reactions and risks There are no related complications and hazards.