Haptens, contact sensitivity

Aiba, S. et al, In vitro treatment of human transforming growth factor-betal-treated monocyte-derived dendritic cells with haptens can induce the phenotypic and functional changes similar to epidermal Langerhans cells in the initiation phase of allergic contact sensitivity reaction, Immunology, 101, 68, 2000. 

Metabolic activation of a,/ -unsaturated oximes, such as 46, leads to the conclusion that this class of unsaturated oximes are pro-haptens. They can undergo epoxidation that eventually produces reactive nitroso intermediates which act as strong contact sensitizers . Here, the oxime function plays a major role in the chemical activation that results in the reactive nitrosoaUcenes. It was further pointed by the authors that oximes can be hydrolyzed in vivo to the corresponding carbonyl compounds which are potential allergens. 

FEHR, B.S., TAKASHIMA, A., MATSUE, H GEROMETTA, J.S., BERGSTRESSER, PR. CRUZ, P.D., JR. (1994) Contact sensitization induces proliferation of heterogeneous populations of hapten-specific T cells. Experimental Dermatology, 3,189— 197. 

XU, H DILULIO, N.A. FAIRCHILD, R.L. (1996) T cell populations primed by hapten sensitization in contact sensitivity are distinguished by polarized patterns of cytokine production. Interferon-y-producing (Tel) effector CD8+ T cells and interleukin (IL) 4/IL-10-producing (Th2) negative regulatory CD4+ T cells. Journal of Experimental Medicine, 183,1001-1012. 

Inhibition of cellular hypersensitivity, such as contact sensitivity, is not readily achieved with simple haptens. DNP-lysine, for instance, did not markedly depress contact reactions to l-chloro-2,4-dinitrobenzene in guinea pigs whereas 2,4-dini-trobenzene sulfonate, which is able to conjugate in vivo, temporarily abolished contact reactions after parenteral injection (de Weck et al. 1964). 

Singer SJ (1964) On the heterogeneity of anti-hapten antibodies. Immunochemistry 1 15-20 Soeberg B, Sumerska T, Binns RM, Balfour BM (1978 a) Contact sensitivity in the pig. II. Induction by intralymphatic infusion of DNP-conjugated cells. Int Arch Allergy Appl Immunol 57 114-125... 

Galindo PA, Garcia R, Garrido JA, Feo F, Fernandez F (1994) Allergic contact dermatitis from colour developers absence of cross-sensitivity to para-amino compounds. Contact Dermatitis 30 301 Hansson C, Ahlfors S, Bergendorff O (1997) Concomitant contact dermatitis due to textile dyes and to colour film developers can be explained by the formation of the same hapten. Contact Dermatitis... 

The induction of skin sensitization and the subsequent elicitation of allergic contact dermatitis are dependent on the development of hapten-specific T lymphocytes. The... 

The allergic variety of contact dermatitis is a type IV hypersensitivity response involving sensitization of T lymphocytes. Antigens form after the sensitizing substance (haptens or partial antigens) comes into contact with the dermal protein fc>r the first time, which results in sensitization. Sensitization may take weeks to years to develop. On reexposure to the same or a related substance, a delayed inflammatory response is elicited, usually within 48 to 72 hours. Allergic contact dermatitis is often associated with the eyelids or periocular area and in some instances may involve the face and the hands. 

Contact (or chemical) hypersensitivity reactions develop in two phases induction and elicitation (Figure 1). Induction is the development of the initial sensitization. In this phase, the chemical penetrates the epidermis. Chemicals are haptens because they are, by themselves, unable to elicit an immune response. As such, they must associate with proteins in the skin to stimulate a specific immune response. The hapten-protein complex is then processed by antigen presenting cells in the skin, transported and presented to T cells in the draining lymph nodes. This interaction leads to a proliferative response and the development of memory T cells that distribute systemically within the body. 

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