Allergic Contact Dermatitis ACD

ACD is a skin reaction resulting from contact dermal contact with allergens. ACD progresses in two phases. Sensitization is acquired in the initial phase. In the second phase, subsequent exposure elicits an inflammatory reaction. F°1 Large numbers of chemical compounds are known to cause ACD. These include acrylates, aldehydes, amines, anhydrides, etha-nolamines, formaldehyde, resins, metals, pesticides, phenols, phthalate esters, preservatives, isocyanates, solvents, and others. Table 27.4 contains a partial list of these. A more complete list can be found on the webJ21l 

ACD has been associated with ethoxylated alcohol surfactants. Though not by themselves known to cause ACD, ethoxylated surfactants are polyethers and are easily air oxidized to hydroperoxides, peroxides, and carbonyl compounds (including formaldehyde and acetaldehyde), substances that do cause ACDJ22 251 The irritant components of surfactants and other chemicals present in formulated products facilitate the absorption of the ACD causing decomposition products of ethoxylated alcohols and thus exacerbate their effects. F61 This is yet another example of lipophilic compounds enhancing the absorption of hydrophilic compounds (the decomposition products of ethoxylated alcohols) and hence increasing the toxic effect beyond that predicted. 

The formation in situ of contact dermatitis producing chemicals is not limited to ethoxylated alcohol degradation. Photocontact allergic dermatitis can be caused by the application of photosensitive chemicals to the skin followed by irradiation with ultraviolet light. Examples of such reactions are discussed in Section 16.4. 

Combinations of allergens have been shown to produce synergistic effects in sensitized individuals. A study was conducted of 18 human volunteers with contact allergies who were exposed to a 1 1 mixture of two fragrance compounds, each of which is known to induce ACD. The mixtures elicited responses that were 3-4 times higher than anticipated 

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Saint-Mezard, P. et al, Afferent and efferent phases of allergic contact dermatitis (ACD) can be induced after a single skin contact with haptens Evidence using a mouse model of primary ACD. J. Invest. Dermatol., 120, 641, 2003. 

Xenobiotics can affect allergic disease in one of two ways. They can themselves act as antigens and elicit hypersensitivity responses, or they can enhance the development or expression of allergic responses to commonly encountered allergens, such as dust mite. Chemicals that act as allergens include certain proteins that can by themselves induce an immune response and low molecular weight chemicals (known as haptens) that are too small to induce a specific immune response but may react with a protein to induce an immune response that is then hapten specific. Haptens have been associated with both allergic contact dermatitis (ACD), sometimes called contact hypersensitivity... 

QSAR, statistical, and computational methods are used to determine the possibility that a material is a sensitizer and the potential severity of sensitization. In vivo methods are useful to diagnose skin disorders such as drug eruptions, contact dermatitis, immediate contact reactions (contact urticaria), and more. Allergic Contact Dermatitis (ACD) is an inflammatory skin disease, marked by a delayed skin response following skin contact with an allergic chemical. Test groups must be very large to assess this effect. To test for ACD, a test article or sample(s) must be initially exposed to the same skin site/area (induction phase). After a rest period of a week or more (others say over... 

Allergic contact dermatitis (ACD) is related to cosmetic contact in many instancesJ33-35 ACD has been shown to arise from contact with different types of cosmetic products. These include... 

It must be pointed out that the vast majority of occupational dermatoses is represented by contact dermatitis [irritant contact dermatitis (ICD), allergic contact dermatitis (ACD), immunoglobulin E (IgE)-mediated reactions] rarely, infectious dermatitis or other forms of dermatitis are encountered. 

A finished composite product only occasionally causes an allergy. Allergic contact dermatitis (ACD) has been reported from limb prostheses made from UP resin (Mac Farlane et al. 1986 Freeman 1986 Vincenzi et al. 1991). ACD has also been caused by unpolymerized epoxy resin in a billiard cue (Gon alo et al. 1992), a screwdriver handle (Fischer et al. 1987) and a mop handle (Jolanki et al. 1992). Glass fibres in a school desk and in printed circuit boards have caused irritant contact dermatitis (ICD) (Koh et al. 1992 Eby and Jetton 1972). 

Diphenylamine (additive in grease) Allergic contact dermatitis (ACD) 69... 

Despite the increasingly more frequent reports of allergic contact dermatitis (ACD) to natural latex, the exact chemical nature of the allergen(s) remains unknown. In contrast, proteins present in latex obtained from the Hevea brasiliensis tree are the cause of the immunoglobulin (Ig)E-mediated hypersensiti-vity/allergic contact urticaria (ACU) to natural latex rubber. Since Hevea brasiliensis accounts for more than 99% of natural rubber used worldwide, ACU to latex is a significant problem. 

Table 1. Relative frequencies of affected skin areas of irritant contact dermatitis (ICD) and allergic contact dermatitis (ACD) among dental personnel (adapted from Miirer et al. 1995a Munksgaard et al. 1996 Rustemeyer and Frosch 1996). Gradations indicate the relative frequencies +++ >80% ++ 40-80% + 20-40% (+) <20%...

The frequency of occupational allergic contact dermatitis (ACD) in dental personnel has increased greatly... 

Adams RM (1990) Forestry workers. In Adams RM (ed) Occupational skin disease. Saunders, Philadelphia, pp 625-626 Asakawa Y (1982) Chemical constituents of the Hepaticae. Prog Chem Org Nat Products 42 1-285 Asakawa Y, Benezra C, Ducombs G, Foussereau J, Muller JC, Ourisson G (1974) Cross-sensitization between Frullania and Laurus nobilis the allergen of laurel. Arch Dermatol 110 957 Asakawa Y, Matsuda R, Toyota M, Takemoto T, Connolly JD, Phillips WR (1983) Sesquiterpenoids from ChiloscyphuSy Clasmatocolea and Frullania species. Phytochem 22 961-964 Barbier P, Benezra C (1982) Stereospecificity of allergic contact dermatitis (ACD) induced by two natural enantiomers, (+)-and (-)-frullanolides, in guinea pigs. Naturwissenschaften 69 296-297... 

Many research have been published that focused on the border between allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD). It is blurred because the two phenomena have commonalities and chemical mediators are, with some nuances, similar in nature, inducing the same order mechanisms. In addition, virtually, the majority of known haptens are irritants because of their chemical reactivity potential. The more the hapten is a powerful irritant, the fewer the necessary amounts will be to raise sensitization. For less irritating haptens, the mixture of the hapten with another irritating substance will greatly facilitate the sensitization. The two mechanisms are closely interdependent. The power of the immunological reactivity of a hapten is proportional to its level of irritation (Fig. 3.26). 

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