Contact allergy to gold as a model for clinical-experimental research.

The high frequency of contact allergy to gold in patients with dermatitis was established after exhaustive skin testing, determining the right test agent, the best concentration, and repeated test readings. Metallic gold in contact with skin is slowly ionized, permitting absorption and haptenisation. Contact allergy to gold is statistically correlated to the presence of dental gold. But in many case reports it has also been attributed to wearing gold jewellery, albeit not statistically demonstrated. Epicutaneous testing with gold salts increases the blood gold level, and by intramuscular injection systemic contact dermatitis is provoked in an allergic individual. In coronary heart disease, gold-coated intravascular stents have been shown to be correlated to contact allergy and even to an increased risk of restenosis. Gold is far from inert.

In vitro lymphocyte reactivity to gold compounds in the diagnosis of contact hypersensitivity.

The use of the lymphocyte transformation test (LTT) in the diagnosis of contact hypersensitivity to gold was studied in 8 patients who had positive patch tests to gold salts, and in 8 control subjects who were negative to such patch tests. Gold sodium thiosulfate and gold chloride were added to cultures of lymphocytes, which were labeled by 3H-thymidine after 96 h. The lymphocyte stimulation index was calculated as the beta-counts in stimulated cultures divided by those in control cultures. The index was statistically significantly higher for the patient group (p=0.005-0.04) than for the control group. Levels of interferon-gamma (IFN-gamma) were determined for the supernatants of the lymphocyte cultures. An index IFN-gamma, which is defined as the level of IFN-gamma in stimulated cultures divided by that in control cultures, was statistically significantly higher for the patient group (p=0.01-0.006). The LTT stimulation index showed specificity and sensitivity between 67 and 80%, the respective values for Index IFN-gamma being between 73 and 100% when the patch test was used as a reference method. Evaluation of lymphocyte reactivity might be of future interest in the diagnosis of allergic reactions to gold if the sensitivity and specificity can be improved.