Immediate and Delayed Hypersensitivity to Mite Antigens in Atopic Dermatitis

Abstract

Atopic dermatitis (AD) is a common disorder and appears to be on the increase, especially among children. It was thought at first to be a manifestation of immediate hypersensitivity, but it is now known that delayed hypersensitivity also plays an important role. Sensitivity to mite antigens is found in 20% to 60% of patients when immediate hypersensitivity is evaluated by the detection of specific IgE antibodies and prick tests, and in 30% to 50% of patients when delayed hypersensitivity is studied by patch testing. A prospective randomized study was carried out in the pediatric dermatology clinic on a sample of 51 children under 15 years of age. A prevalence of immediate and delayed hypersensitivity to mites, like that described for other populations, was found. It was further found that there was a positive association, not described in the literature, between the younger age groups and delayed hypersensitivity to mite antigens, while the opposite was true for immediate hypersensitivity. We believe that patch tests with airborne allergens, specifically mites, should be part of the protocol for assessing children with AD, particularly in the younger age groups.

Is the Atopy Patch Test with House Dust Mites Specific for Atopic Dermatitis?

“…In studies performed on APT the percentages of positive subjects varied [7, 10, 14, 16], and this was ascribed to the absence of standardization in employed techniques and to the different purification and concentration of allergens [3, 9,16,17,18, 32]. At present, the technique most frequently employed is the application of extracts on healthy untreated upper back skin [3].…”

“…Many studies on the APT have been performed [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24], and it is regarded quite specific for patients with AD. However, small numbers of positive APT were reported in the past also in atopic subjects without dermatitis [6, 8,18,19,20, 23, 24] and in healthy persons [5, 9, 11, 13,18,19,20, 23, 24] and that would raise some question about the specificity and the clinical relevance of positive APT results.…”

Chymase Participates in Chronic Dermatitis by Inducing Eosinophil Infiltration

“…The patients with AD often have a family history of other allergic diseases including asthma and hay fever. Although AD is known to be a manifestation of immediate hypersensitivity mediated by IgE, delayed-type hypersensitivity is also involved in the skin reaction of the patients (Tanaka et al, 1994;Varela et al, 1999). Interestingly, in mice, repeated application of contact sensitizing agents, such as 2,4-dinitrofluorobenzene (DNFB) and trinitrochlorobenzene, develops an immediate-type reaction, in contrast to a single application that causes a typical delayed-type reaction (Kitagaki et al, 1995(Kitagaki et al, , 1997.…”

Characterization of Spontaneous Dermatitis in Beige Rats with IgE Hyperproduction

“…Beige rats showed a high susceptibility to the maximization test, suggesting high skin contact sensitivity. As the high positivity of a patch test with house dust mites was found in human AD, contact hypersensitivity also played an important role in the progression of AD [14, 28]. Taken together, type I allergy and high contact sensitivity may be involved in the initiation and acceleration of dermatitis in beige rats.…”

“…Degranulated mast cells have been reported to be prominent in acute dermal lesions of AD [13]. AD was thought to be a manifestation of type I allergy, but it is known that type IV allergy also plays an important role [14]. Recently, an important role in the induction is suggested for IgE-bearing epidermal Langerhans and non-IgE-bearing mast cells in human AD [5].…”