Contact hypersensitivity (CHS) is a T cell-mediated, Ag-specific skin inflammation induced by skin exposure to haptens in sensitized individuals. Th1/T cytotoxic 1 cells are effector cells of CHS, whereas Th2/T regulatory CD4+ T cells have down-regulating properties. We have previously shown that CHS to 2,4-dinitrofluorobenzene is mediated by specific CD8+ effector cells, whose cytolytic activity is mandatory for induction of skin inflammation. In this study, using immunohistochemistry and RT-PCR analysis, we show that CD8+ T cells are rapidly recruited into the skin at the site of hapten challenge before the onset of clinical and histological signs of skin inflammation. This early CD8+ T cell recruitment is concomitant with: 1) transient IFN-γ mRNA expression suggesting local activation of effector cells; and 2) induction of keratinocyte (KC) apoptosis which gradually increased to a maximum at the peak of the CHS response. Alternatively, skin infiltration of CD4+ T cells occurred later and coincided with the peak of the CHS reaction and the beginning of the resolution of skin inflammation. Mice deficient in CD8+ T cells did not develop CHS, whereas mice deficient in CD4+ T cells developed an enhanced inflammatory response with increased numbers of CD8+ T cells recruited in the skin associated with massive KC apoptosis. These data show that CHS is due to the early and selective recruitment in the skin of CD8+ T cytotoxic 1 effector cells responsible for KC apoptosis.

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A survey of psoriasis patients from 1982-2001 has been reported by the Japanese Society for Psoriasis Research. The aim of this study is to analyze psoriasis patients in Japan registered from 2002-2008. A total of 11 631 cases were registered from 152 dermatological institutions in Japan. Males (7738 cases, 66.5%) were predominant over females (3893 cases, 33.5%). The clinical types of psoriasis were psoriasis vulgaris (88.5%), guttate psoriasis (3.9%), psoriasis arthropathica (3.3%), generalized pustular psoriasis (1.3%), psoriatic erythroderma (1.2%), localized pustular psoriasis (0.9%) and infantile psoriasis (0.1%). Topical corticosteroids (85.4%) and vitamin D(3) (59.7%) products were the main previous topical agents. Previous systemic treatments included etretinate (8.8%), cyclosporin (8.3%) and methotrexate (2.0%). Use of topical vitamin D(3) and systemic cyclosporin therapies has been increasing during the past 7 years. Topical psoralen and ultraviolet A therapy (PUVA) (7.6%) was the predominant phototherapy followed by UV-B (7.3%) and systemic PUVA (4.7%). Use of UV-B phototherapy has been increasing during the past 5 years. The survey of Japanese psoriasis patients during 2002-2008 disclosed that psoriasis arthropathica is more prevalent (1%) than that of the previous survey during 1982-2001. Use of topical vitamin D(3) and systemic cyclosporin has been increasing during the past 7 years.