Allergic Contact Dermatitis in Patients with Atopic Dermatitis

Exploring the relationship between allergic contact dermatitis and atopic dermatitis in children: insights from a retrospective patch testing analysis

BACKGROUND

Recent years have seen significant exploration into the potential link between allergic contact dermatitis and atopic dermatitis, yielding contradictory findings.

METHODS

A retrospective cohort analysis of children aged 2 to 18 who underwent patch testing at the pediatric dermatology clinic at a tertiary medical center in Israel was conducted.

RESULTS

Overall, 367 patients were included in the study, 31.6% of whom were diagnosed with atopic dermatitis. 160 children (43.6%) exhibited a positive reaction to at least one compound in the European baseline series. There was no statistically significant difference in reactivity between children with atopic dermatitis and those without (P = 0.848). Sub-analyses based on ethnicity, gender, and age did not reveal significant differences in overall European baseline series reactivity (P = 0.612, P = 0.446, P = 0.488, respectively). Sensitivity was notably higher when patch readings were conducted 72 h after application compared to 48 h [0.95 (CI: 0.91-0.97) vs. 0.60 (CI: 0.55-0.66)].

CONCLUSIONS

Patch testing is imperative for suspected cases of allergic contact dermatitis in all children, regardless of their atopic background. Further research is warranted to potentially replace the traditional 48-h reading with a single 72-h reading in future guidelines, contributing to enhanced efficiency and cost-effectiveness in clinical practice.

Tolerogenic phenotype of dendritic cells is induced after hapten sensitization followed by attenuated contact hypersensitivity response in atopic dermatitis model NC/Nga mice

Allergic contact dermatitis (ACD) and atopic dermatitis (AD) are common inflammatory diseases. We previously reported attenuated contact hypersensitivity (CHS) responses in AD model mice using 2,4-dinitrofluorobenzene, reflecting clinical experiments. However, previous studies have not addressed the commonality of findings across haptens and mechanisms focused on dendritic cells (DCs). Thus, this study evaluated CHS responses to fluorescein isothiocyanate (FITC) and DC migration and maturation in the sensitization phase of CHS in AD. CHS responses to FITC were compared between NC/Nga mice without and with AD induction (non-AD and AD mice, respectively). T-cell responses and DC migration and maturation after FITC-induced sensitization were examined in the draining lymph nodes of non-AD and AD mice. AD mice demonstrated reduced CHS responses to FITC under decreased T-cell proliferation following sensitization and interferon-γ production by hapten-specific T cells compared with non-AD mice. In addition, the number of FITC+CD11c+MHC class IIhigh migratory DCs 24 h after FITC sensitization was comparable between non-AD and AD mice. However, FITC+CD11c+MHC class IIhigh migratory DCs in AD mice exhibited lower expression levels of CD80 and CD86 and higher expression levels of PD-L1 and mRNA of transforming growth factor beta than non-AD mice. These findings suggest that attenuated CHS responses may be hapten-independent and the induction of the tolerogenic phenotype of hapten-bearing DCs can contribute to reduced T-cell proliferation after sensitization and CHS responses in AD.