Increased retest reactivity by both patch and use test with methyldibromoglutaronitrile in sensitized individuals

Hyperreactivity on re-exposure of previous allergic contact dermatitis skin areas has been previously demonstrated. This study aimed to investigate in methyldibromoglutaronitrile (MDBGN) allergic patients whether skin with previous allergic dermatitis from MDBGN showed an augmented response on re-exposure by both a patch test challenge and a use test with a liquid soap preserved with MDBGN. MDBGN dermatitis was elicited on the back and arms of sensitized individuals. One month later the previously eczematous areas were challenged with MDBGN. On the back, the test sites were patch-tested with a serial dilution of MDBGN and a use test was performed on the arms with an MDBGN-containing soap. A statistically significant increased response was seen on the areas with previous dermatitis on the back. Eight of the nine patients who developed dermatitis on the arms from the MDBGN-containing soap had an augmented response on areas with prior allergic contact dermatitis. Even though the allergic dermatitis appeared to be healed, an increased reactivity to allergen re-exposure was demonstrated both by patch test and use test challenge.