Polysensitization and increased susceptibility in contact allergy: a review

Abstract

Genetic factors presumably play a role in contact allergy (CA). There is, however, a lack of conclusive evidence from clinical studies. This may be on account of the strongly competing or modifying impact of exogenous factors, namely the potency of allergens and the intensity of exposure, and the fact that – in principle – everybody can be sensitized. Regarding phenotype, in contrast, polysensitization (PS) seems to indicate a subset of individuals at greater risk. In human sensitization experiments with dinitrochlorobenzene, induction was facilitated in PS, and elicitation enhanced. Recent clinical epidemiological data, taking confounders for PS, such as age, sex, and other skin diseases into account, demonstrated the following: (i) PS was the greatest risk factor to be sensitized to a number of (even weak) index allergens, indicating higher susceptibility on the level of induction; (ii) patch test reactions in PS patients were generally stronger indicating higher susceptibility on the level of elicitation. These findings are complemented by reports on polymorphisms of TNF‐α and IL‐16 in PS patients. Future studies on the genetics of CA should be performed in subgroups with PS, focussing on polymorphisms relevant for CA‐specific and nonspecific (inflammatory) processes.

Impact of the magnitude of sensitization dose on the incidence and intensity of CHS to dinitrochlorobenzene (DNCB): Insight from ear swelling and challenged-skin draining lymph node response in rats

“…Increases in the proportion of animals that responded to challenge more vigorously than sensitization control by ear swelling, as well as a more intense response following challenge of animals sensitized with 4% DNCB (compared to response in rats sensitized with 0.4% DNCB), suggests the dependency between rat CHS and DNCB concentration. These results are in concordance with human studies with DNCB that showed that degree of sensitization-measured as skin-fold thickness at a constant challenge dose-increased as the sensitizing dose increased (Friedmann, 2007;Schnuch et al, 2008). A low incidence of responsiveness to challenge in animals sensitized with 0.4% DNCB might have accounted for the slight (solely numerical) increase in ear swelling among the challenged animals sensitized with this dose.…”

Risk factors of polysensitization to contact allergens

“…to be polysensitized. Risk factors included a priori in the model, based on previous, related analyses, 2 were age, sex, atopic eczema (past or current), occupational causation of dermatitis, duration of application of the patch test (48 vs. 24 h) and anatomical site of dermatitis. Additionally, the number of individually tested allergens was controlled for, as this evidently is associated with the outcome (firstly, the length of different versions of baseline series differs to some extent; secondly, allergens are occasionally omitted on a case by case basis).…”

“…12 Furthermore, those allergens with a low proportion of no additional reactions can be considered as (very) weak allergens, which have already been shown to be associated with PS. 2 Hence, PS is a phenomenon structured by certain groups or clusters of haptens. When interpreting the results presented in Table 3, it should be kept in mind that the novel approach of deriving two separate estimates is difficult to compare with previous results in quantitative terms.…”

“…Regarding the definition and applications of the concept of PS, basically to identify persons who are apparently easier to sensitize than others, we refer to previous reviews on this topic. 1,2 To date, different statistical approaches have been used to examine the factors associated with PS, namely: (i) crude, bivariate analyses; (ii) logistic regression analysis; and (iii) nominal and ordinal regression analysis, using an (ordered) categorical outcome. The present analysis intended to utilize the maximum information available in the original count data (individual number of positive reactions to baseline series allergens).…”

Individual Susceptibility to Occupational Contact Dermatitis

“…Although there is no generally accepted definition, polysensitization refers to existence of multiple allergies in an individual 34,92) . Based on experimental and clinical findings, it has been reported that polysensitized patients are more easily sensitized to a further allergen, and that they exhibit a stronger reaction after elicitation 93) .…”