Nickel (Ni) is the most frequent cause of contact allergy among the female population. This makes it interesting to examine thresholds for elicitation under different conditions. Even though Ni exposure may be open, occluded, penetrating or oral, most dose-response studies in the literature concern single occluded application. The aims of this study were to assess thresholds of response by making a statistical analysis of available dose-response studies with single occluded exposure and comparing the results to thresholds from other modes of exposure. 8 occluded Ni dose-response studies were selected based on statistical considerations. The statistical analysis showed that 5% of a sensitized population react to 0.44 mg Ni/cm 2 and 10% react to 1.04 mg Ni/cm 2 . In another study with a single open application, 7.8% of sensitized persons responded to a dose Â6 higher than the dose to which 10% reacted in occluded exposure. When combining the exposure to Ni with an irritant, divagating results were found, although the literature shows evidence of an augmented response when combining exposure to an allergen and an irritant. The thresholds of penetrating exposure were found to be lower than the thresholds of single occluded exposure. Comparisons of different kind of exposures across studies are difficult, because of differences in the studies, although a comparison could be made by a study that compares the different exposures within the same individuals at the same time.

For elicitation of nickel allergy the elicitation threshold for the patch test is higher than the elicitation threshold (per application) for the ROAT, but is approximately the same as the accumulated elicitation threshold for the ROAT. This may be important for risk assessment based on dose-response results from allergic patients.

PASS syndrome is a rare inflammatory disease characterized by a chronic-relapsing course of pyoderma gangrenosum, acne vulgaris, hidradenitis suppurativa and ankylosing spondylitis. Here, we describe a case of a patient with spontaneously recurrent purulent skin lesions along with seronegative spondylarthritis consistent with the PASS syndrome. During his disease exacerbation, the patient displayed episodes of fever along with elevated serum levels of interleukin (IL)-1β. Skin lesions were characterized by sterile neutrophilic infiltrates and showed a rapid response to the IL-1 receptor antagonist anakinra (Kineret®) consistent with the autoinflammatory nature of this disease. However, unlike other autoinflammatory diseases such as PAPA and PAPASH, we did not find mutations in the gene PSTPIP1, raising the possibility that other specific mutations in the IL-1 pathway may be involved.

This equation may be used for non-volatile compounds other than nickel and MDBGN, after further validation. The relationship between the patch test and the ROAT can be used for prevention, to set safe levels of allergen exposure based on patch test data.