phytohemagglutinin intradermal test

Skin tests are the most commonly used in vivo test methods for measuring cellular immune function. Its essence belongs to delayed type hypersensitivity (type IV). When the body is infected by some bacteria (such as Mycobacterium tuberculosis, Brucella), viruses, or fungi, or contact with small molecules, hapten substances, when combined with tissue proteins in the body to become a complete antigen. The body produces specific sensitized lymphocytes against these antigenic substances. When the corresponding antigen re-enters the body, the local sensitized lymphocytes release a variety of lymphokines. After 24 to 72 hours, the inflammation caused by mononuclear cell infiltration is manifested as redness and induration of the skin. This reaction is called delayed type. allergy. This reaction can be used as one of the indicators for judging the cellular immune function of the body. Basic Information Specialist classification: inspection classification: immune examination Applicable gender: whether men and women apply fasting: not fasting Analysis results: Below normal: Normal value: no Above normal: negative: 1. Seen in cell immunodeficiency disease, some leprosy patients (about 50% to 70% negative) and severe acute and chronic hepatitis, subacute hepatic necrosis, measles, tuberculosis, etc. 2. PHA reactions such as advanced solid tumors and chronic lymphocytic leukemia may be negative. Positive: 1. Normal; 2. The positive rate of malignant tumors with metastasis is only 5% to 10%; 3. The positive rate of patients with benign tumors or non-metastatic malignant tumors is similar to that of normal people. Reminder: The female skin test response is significantly higher than that of men. The response is the weakest under the age of 9 and gradually increases with age. More than 30 years old showed a relatively strong reaction period. This test can be used in various age groups and is more suitable for children. Normal value Positive with induration diameter ≥ 5mm. Using a 5 μg PHA skin test, the redness of the red blood was 8.5 ± 0.1 mm positive; With a 10 μg PHA skin test, the redness was 11.2 ± 0.4 mm positive. Clinical significance (1) Those with low cellular immune function, negative reaction, less than 5mm in diameter, such as tuberculosis, measles and rubella infection. (2) Tumor patients gradually inhibit with the development of the disease, and are related to the prognosis of the disease, such as advanced solid tumor, severe lymphoblastoma, chronic lymphocytic leukemia and other PHA reactions can be negative. Negative results may be diseases: chronic lymphocytic leukemia, measles, tuberculosis precautions 1. Within a few minutes after the PHA skin test, local erythema often appears in the injection site, and gradually disappears within a few hours. It does not need to be measured. After 5-6 hours, the erythema induration may gradually appear. Most of them reach the peak at 24 hours, and then begin to subside after 24 hours. The results were measured within 18 to 24 hours. 2. The difference between the normal person and the skin test is large, and it is affected by the observation time, dose and depth of injection. When a negative is encountered, a retest or a simultaneous in vitro cellular immune function assay should be performed for comparison. 3. Very few patients can develop anaphylactic shock during skin test, often starting within a few seconds to 5 minutes after injection, first itchy skin, numbness of the limbs, followed by shortness of breath, chest tightness, cyanosis, rapid heartbeat, fine pulse, blood pressure drop A large amount of sweating, etc., if not rescued in time, can lead to death of the patient. Therefore, you should be prepared for rescue, such as standing adrenaline hydrochloride, hydrocortisone, central stimulants and anti-allergic drugs. Inspection process (1) Take PHA1 (containing 10 mg/dose) and dilute with physiological saline to 5, 10 or 20 μg per 0.1 ml. Disinfect the inner skin of the forearm with a 1 ml syringe to extract a proper amount of the drug solution, and inject 0.1 ml into the skin to form a white vesicle locally. (2) After 18~24h, the diameter of local redness and induration was measured, generally >5mm was positive, but the redness often began to fade at 24h, and there was no obvious redness after 48h. The normal person used 5μg PHA skin test, the positive rate was 100%, the redness was 8.5±0.1mm, and the 10μg PHA skin test was used. The positive rate was 100%, and the redness was 11.2±0.4mm. The female skin test response was significantly higher than that of men. The response is the weakest under the age of 9 and gradually increases with age. More than 30 years old showed a relatively strong reaction period. This test can be used in various age groups and is more suitable for children. Not suitable for the crowd A person with a history of anaphylactic shock. Adverse reactions and risks Very few patients can develop anaphylactic shock during skin test, often starting within a few seconds to 5 minutes after injection, first itchy skin, numbness of the limbs, followed by shortness of breath, chest tightness, cyanosis, rapid heartbeat, fine pulse, blood pressure drop, a large number Sweating, etc., if not rescued in time, can lead to death of the patient. Therefore, you should be prepared for rescue, such as standing adrenaline hydrochloride, hydrocortisone, central stimulants and anti-allergic drugs.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.