THE SIGNIFICANCE OF PREVIOUS CONTACT-DERMATITIS FOR ELICITATION OF CONTACT ALLERGY TO NICKEL

In 2 earlier studies, we found increased nickel re-test reactivity at earlier experimentally induced nickel eczema sites. The aim of this st udy was to investigate if earlier contact dermatitis caused by another allergen or earlier irritant contact dermatitis also influenced the r eactivity when nickel was applied topically on earlier but healed derm atitis sites. Twenty-three females with contact allergy to both nickel and cobalt were involved in the study. Experimental contact dermatiti s from nickel, cobalt and SLS was induced on the lower back. One month later, challenge patch testing with a serial dilution of nickel on th e previous but healed dermatitis sites, and on a control area, was don e. The tests were read blindly. Significantly higher test reactivity w as found at the site with previous allergic contact dermatitis from ni ckel, and significantly lower test reactivity was observed at the prev ious SLS dermatitis site.