'Irritants' increase the response to an allergen in allergic contact dermatitis

Iodopropynylbutyl carbamate 0.2% is suggested for patch testing of patients with eczema possibly related to preservatives

“…This finding relates very well to the previously reported high irritancy of 0·5% IPBC 2 . With 0·5% IPBC the well‐known irritant effect of IPBC probably leads to such an augmentation of the response that many nonallergic reactions are read as positive ones (false‐positive reactions), 33 and that weak true‐positive reactions tend to become stronger positive reactions, hence the somewhat lower positivity ratio. It has been shown that irritants can in fact elicit crescendo reactions; 16,21 this capability may contribute to a nonspecific delayed amplification of weak reactions.…”

Subtoxic concentrations of allergenic haptens induce LC migration and maturation in a human organotypic skin explant culture model: a novel method for identifying potential contact allergens

“…In mice, proliferation of lymph node cells can be found after stimulation with SDS, a model skin irritant (43). Several published data in literature demonstrated that partly cytotoxic irritant concentrations activate DC in vitro cultures (51) and similar findings had also been observed by us [see the accompanying manuscript (47)]. Further, several other reports concerning the in vivo studies on adjuvant effects (52–55) also suggest that the irritation properties of the haptenes need to be taken into consideration before the chemicals can be categorized as true sensitizers and not just irritants.…”

Augmentation of skin response by exposure to a combination of allergens and irritants – a review

“…When evaluated by clinical scoring and colourimetry, the response was found to be synergistic. This difference from the findings of McLelland et al (4) is probably due to the use of more advanced statistical analysis.…”