The haptenation theory of vitiligo and melanoma rejection: a close-up

The 'Haptenation theory' concerns the multicausal pathogenesis of vitiligo ending ultimately in the (partial) disappearance of melanocytes from the skin and/or hairs. The melanocyte specificity is attributed to the tyrosinase-catalysed production of haptogenic ortho-quinones that covalently bind to tyrosinase or other melanosomal proteins to generate neo-antigens. These latter, in turn, trigger an immunological cascade resulting in a melanocyte-specific delayed-type hypersensitivity reaction that eliminates melanocytes and produces the characteristic depigmentation. This causal chain of events is critically discussed with special reference to factors modifying the process and the possible influence of various biochemical changes, such as raised levels of catecholamines and epidermal hydrogen peroxide, which have been reported to be associated with the onset of vitiligo. This all adds up to the typical vitiligo reaction pattern or syndrome, which demands a treatment strategy involving most of the already known therapies. Similar pathogenetic mechanisms might be engaged in the enhancement of cellular immunity (vaccination) against melanoma.