Contact allergy (overview) L23.9

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 11.12.2021

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Definition
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Antigen-specific, T-cell-mediated, delayed type IV immune response (Gell and Coombs) that occurs after repeated exposure to contact allergens. (see below allergy, type IV reaction) can occur in persons with the appropriate disposition. The predisposition can be based on genetic or non-genetic factors (see below contact allergy, genetics). Other non-specific factors such as infections can also be involved in the initiation of the contact allergic reaction.

The most frequent contact allergens are metal allergens(nickel) followed by cosmetics, creams, light protection agents and externally applied drugs. Typical for a contact allergic reaction are scattering reactions, which can often occur in the immediate vicinity of the contact site but also far away as a systemic scattering reaction.

Less frequent are so-called contact allergies of the immediate type (detection by atopy patch test), a type IV reaction triggered by type I allergens - here the most frequent triggers are plant and animal products.

Occurrence/Epidemiology
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The 10 most common allergens in children (0-12 years) and non-working adults (> 17 years) varies according to M.Wort et al (2015)

Test substance (children) Children (% positive) Test substance (adults) Adults (% positive)
Nickel sulphate 8,5 Nickel sulphate 11,5
Fragrance mix 5,5 Fragrance mix 8,4
Rosin 3,4 Peru Balsam 7,8
Fragrance Mix II 3,1 Cobalt chloride 5,3
MCI/MI(Methylisothiazolinone) 2,2 Fragrance Mix II 5,0
Thiuram mix 2,1 Potassium dichromate 4,0
Mercaptobenzothiazole 1,8 Rosin 3,7
Mercapto Mix 1,8 MCI/MI(Methylisothiazolinone) 3,2
Bufexamac 1,4 Dibromdicyanobutane 3,1
Dibromdicyanobutane 1,2 Propolis 3,0

Remarkably, a lower frequency of contact allergies is detectable in psoriatic patients (Claßen et al.2017).

Etiopathogenesis
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Allergic contact dermatitis (contact eczema) is the prototype of a cell-mediated immune reaction of the late type (DTH = delayed-type hypersensitivity, type IV reaction according to Coobms and Gell). Basically, according to our ideas, this reaction proceeds in 2 phases:

Sensitization phase:

  • In the sensitization phase, keratinocytes and dermal mast cells are stimulated to produce large amounts of interleukin-1 and TNF-alpha shortly after application. These are responsible for the maturation of Langerhans cells into immunostimulating dendritic cells (DCs). Antigen-loaded dermal dendritic cells (DDCs) enter the draining lymph nodes. There, they present the MHC antigen complex to naïve T cells (see antigen presentation below) that carry the T cell receptor matching the antigen (or hapten protein complex). This triggers a Th1/Tc1 and Th17/Tc17-predominant T cell response.
  • Haptens activate the ERK1/2 mitogen-activated protein kinase (see MAP kinase signaling pathway below) in human dendritic cells by binding to thiol groups. Similarly, they induce enhanced expression of interleukin 1-beta mRNA. Hapten-activated keratinocytes express more TNF-alfa, IL-1ß, GM-CSF, chemokines, adhesion molecules (LFA-1 and ICAM-1 see below Integrins).
    • Langerhans cells activate the T cell interaction of the MHC I (major histocompatibility complex) or MHC II presenting hapten with the hapten-specific T cell receptor.
    • Alternatively, activation occurs via costimulatory molecules, e.g. B7-1, B7-2, ICAM-1. Both signals together lead to activation and clonal expansion of hapten-specific CD4 and CD8 cells, which are able to migrate into the skin by their pattern of adhesion molecules and chemokine receptors (specific homing).

Secondary antigen contact (trigger phase):

  • Re-contact with the same allergen leads to activation of antigen-specific memory cells. These develop into effector cells that initiate an inflammatory reaction (clinical: erythema, edema, itching, vesiculation, scaling; immunological: cytokine release, recruitment of further inflammatory cells). Immunological process: Specific memory T cells, which are activated after renewed contact with the antigen and transform into effector cells, are initiators of the inflammatory reaction, but not its executors. CD4+ and CD8+ T cells are mainly involved in the triggering phase of AKD. The number of CD8 T cells increases in the skin 6-18 hours after contact with the hapten and is accompanied by an increase in IFN-gamma. Nonspecific inflammatory cells (e.g. neutrophil granulocytes, mast cells, macrophages) act as executors.
  • New contact with haptens leads directly and concentration-dependently to:
    • Increased expression of surface molecules and production of cytokines by epidermal cells as well as endothelia. In this process, a certain non-specific irritative activity of the hapten is a prerequisite for the triggering of an allergic contact allergy.
    • Recruitment of antigen-specific T cells to the site of Ag contact by inflammatory signals to release chemokines and cytokines from keratinocytes.
    • Activation of endothelial cells, as presentation of antigen to T cells can only occur extravascularly, and expression of adhesion molecules, e.g. E-, L-, P-selectin; ICAM-1, LFA-1, CD18.

Cutaneous inflammatory response:

  • After hapten-specific activation, cytotoxic T lymphocytes (CTL) lyse the hapten-modified (and thus attackable) keratinocytes. This results in the release of inflammatory mediators, recruitment of mononuclear cells, and amplification of the immune response. In addition, both TH1 and TH2 cells produce cytokines and mediators (e.g. INF gamma, TNF-alpha, IL-12), which also lead to an amplification of the response locally. Substance P and CGR peptides (calcitonin gene related peptide) also act in terms of an enhanced inflammatory response. This is in contrast to the effects of IL-4 and IL-10, which are produced by CD4+ TH2 cells and are involved in a negative regulation of AKD. This also applies to some neuropeptides, such as alpha-MSH and the vasoactive intestinal peptide (VIP).
    • Antigen-specific T cells can stimulate resident mast cells to produce TNF-alpha as well as MIP-2/IL-8. TNF-alpha induces expression of adhesion molecules that enable neutrophil granulocytes to bind to vascular endothelia. MIP-2/IL-8 establishes a chemotactic gradient responsible for transvascular diapedesis and pinpoint migration to the tissue locus contacted by haptens.

Manifestation
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Contact allergy is a common disease. 15-20% of the general population is sensitized to one of the common contact allergens. Manifestly about 8% of adults and 5-6% of children get sick once in a lifetime. Sex-specific differences are not found.

Note(s)
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Current data on the incidence of allergic diseases in children show 12-month prevalence data for allergic rhinitis of 9.1%, atopic eczema of 6.0% and bronchial asthma of 4.1% (Worm M et al. ).

Literature
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  1. Claßen A et al. (2018) The frequency of specific contact allergies is reduced in patients with
  2. psoriasis. Br J Dermatol doi: 10.1111/bjd.17080.
  3. Davies EE et al (2007) Para-phenylenediamine allergy from a henna tattoo. Arch Dis Child 92: 243
  4. Flint MS et al (2003) Differential regulation of sensitizer-induced inflammation and immunity by acute restraint stress in allergic contact dermatitis. J Neuroimmunol 140: 28-40
  5. Kawase Y et al (2003) Exacerbated and prolonged allergic and non-allergic inflammatory cutaneous reaction in mice with targeted interleukin-18 expression in the skin. J Invest Dermatol 121: 502-509
  6. Krüger U, Fuchs Th (2007) Contact urticaria and protein contact dermatitis in occupational dermatology. Derm Occupation and Environment 55: 107-111
  7. Marchese C et al (2003) Nickel-induced keratinocyte proliferation and up-modulation of the keratinocyte growth factor receptor expression. Exp Dermatol 12: 497-505
  8. Mascia F et al (2003) Blockade of the EGF receptor induces a deranged chemokine expression in keratinocytes leading to enhanced skin inflammation. Am J Pathol 163: 303-312
  9. Meingassner JG et al. (2003) Pimecrolimus inhibits the elicitation phase but does not suppress the sensitization phase in murine contact hypersensitivity, in contrast to tacrolimus and cyclosporine A. J Invest Dermatol 121: 77-80
  10. Moulon C et al (2003) T cell receptor transfection shows non-HLA-restricted recognition of nickel by CD8+ human T cells to be mediated by alphabeta T cell receptors. J Invest Dermatol 121: 496-501
  11. Plitz, T et al. (2003) IL-18 binding protein protects against contact hypersensitivity. J Immunol 171: 1164-1171
  12. Riemann H et al (2003) Pathomechanisms of the triggering phase of allergic contact dermatitis. JDDG 1: 613-619
  13. Schnuch A (2013) Genetics of contact allergy. Dermatologist 62: 732-738
  14. Schnuch A et al (2015) Common disease of contact allergy. Dermatologist 66: 644-645
  15. Uter W et al (1999) The MOAHLFA index in 17 centers of the Information Network of Departments of Dermatology (IVDK) over 6 years. Contact Dermatitis 41: 343-344
  16. Wildemore JK et al (2003) Evaluation of the histologic characteristics of patch test confirmed allergic contact dermatitis. J Am Acad Dermatol 49: 243-248
  17. Zhai H et al (2003) Provocative use test of nickel coins in nickel-sensitized subjects and controls. Br J Dermatol 149: 311-317

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Please ask your physician for a reliable diagnosis. This website is only meant as a reference.

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Last updated on: 11.12.2021