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| | eMedicine - Delayed-type Hypersensitivity : Article by Harumi Jyonouchi, MD |
 | | Pathophysiology: A DTH reaction in the skin is initiated when certain antigens are presented by antigen-presenting cells (APCs) in the skin (ie, Langerhans cells) to sensitized memory T cells. |
 | | DTH skin test reactions are absent in patients with lepromatous leprosy (M leprae), sarcoidosis, coccidioidomycosis, schistosomiasis, rheumatological diseases, severe viral infections (eg, influenza, mononucleosis, mumps), and those given MMR recently (up to 3 wk). |
 | | DTH skin test reactivity to most antigens is read as positive when induration is greater than or equal to 5 mm at 48 and 72 hours following inoculation. |
| www.emedicine.com /ped/topic558.htm (6123 words) |
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