The most striking and constant finding was the dramatic

decrease of dendritic (CD1a+CD2–CD3–) cells from early to late lesions, encompassed by an increase in the proportions of total T cells. These are the only statistically significant (PStudent’s t < 0·05) differences between the two groups of patients. The proportions of helper and cytotoxic T cells; B cells, activated cells and natural killer (NK) cells were not significantly different. In previous studies we have demonstrated that peripheral blood lymphocyte subsets are not different in patients with vitiligo than in normal individuals, despite the time of evolution of the disease; therefore, it seems that these changes are localized to the skin lesions and do not result from a central disorder. Also unexpected was the scant number of B cells check details in early stages of the disease and its practical absence in late stages of the disorder. The core finding of this study is suggestive of the possibility that the immune self-reactivity seen in vitililgo is antigen-driven, rather than spontaneous. For a long time it has been considered that triggering of autoimmune reactants, mainly

autoantibodies, does not follow the regular pathway as non-self-antigens. Anti-DNA antibodies, for instance, are not known to be produced Antiinfection Compound Library after DNA fragments are presented to T cells by major histocompatibility complex (MHC) molecules in antigen-presenting cells in patients with systemic lupus erythematosus, nor are rheumatoid factors believed to be produced after IgG molecules or immune complexes are presented to the immune system. For the vast majority of autoantibodies it is believed that autoreactive clones are ‘freed’ from regulatory mechanisms, thus

resulting in the spontaneous activation of such clones and the synthesis and Carnitine palmitoyltransferase II secretion of their autoantibody products [30]. Polyclonal activation, superantigens, equivocal co-operation and other mechanisms have been mentioned and proposed; however, it is thought generally that specific antigen-driven responses are not involved in autoimmune diseases [30]. The finding of abundant dendritic cells in infiltrates from early biopsies suggests strongly that an antigen-presentation process is taking place at this stage of the pathogenetic process. It is possible, therefore, to hypothesize that a primary non-autoimmune phenomenon causes the breakdown of melanocytes. This primary process, which could be traumatic, physical or infectious, might result in the exposure and uptake of intracellular melanocyte-associated antigens by professional antigen-presenting cells and – in individuals with genetic susceptibility – trigger a ‘traditional’ T cell-dependent immune response towards previously hidden self-antigenic structures.