LONG-LASTING ALLERGIC PATCH TEST REACTION CAUSED BY GOLD

Allergic contact dermatitis caused by gold is rare, and only isolated cases have been reported. Patch testing with gold may cause a long-las ting reaction. The purpose of this study is to describe a well-studied case of gold allergy caused by dental gold crowns. A gold-sensitized patient and a non-sensitized control subject were examined using patch tests, inimunohistochemistry, electron microscopy and blast transform ation reactions. Sodium thiosulfate, auranofin and sodium thiomalate g ave positive patch test reactions. Immunohistochemistry and electron m icroscopy were performed from biopsies taken from allergic patch test reactions caused by gold sodium thiosulfate 1 day and 17 days after ap plying the patches, from normal skin and from a 17-day-old allergic pa tch test reaction caused by ammonium persulfate. Down-regulation had t aken place by 17 days in the allergic ammonium persulfate reaction, bu t not in the 17-day allergic gold test reaction. The patient reacted t o all but one of the gold-induced blast transformation tests, sodium c hloroaurate being non-inductive. The non-sensitized control subject di d not exhibit any reactions. In conclusion, gold sodium thiosulfate, g old sodium thiomalate and auranofin can be used as patch test substanc es for gold allergy, though long-lasting allergic patch test reactions may develop. In vitro gold salt induced blast transformation is an al ternative test for gold allergy. The slow down-regulation of the aller gic patch test reactions needs to be studied further.