الفهرس 
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Abstract
Vitiligo is an autoimmune skin disease in which melanocytes, the pigment-producing cells of the skin, are targeted for destruction by autoreactive CD8+ T cells. As a result, patients develop patchy white spots on their skin. Vitiligo affects roughly 1% of the population (Riding and Harris, 2019).
Melanocyte-specific, cytotoxic CD8+ T cells have been strongly implicated in the destruction of melanocytes in multiple studies. CD8+ T cell infiltration of the epidermis and dermis has been demonstrated histologically, in addition, higher numbers of cytotoxic CD8+ T cells in the blood were found in patients with vitiligo compared to healthy controls (BenzekriandGauthier,2017). Cytokines are key mediators of melanocyte loss in vitiligo and participate at every step of the pathogenesis of this disease (Migayron et al., 2020).Previous studies have demonstrated increased expression of inflammatory cytokines in skin and circulation among vitiligo patients (Rajendiran et al., 2020).
The mechanism of melanocyte loss in vitiligo is possibly related to keratinocyte-derived cytokines that stimulate melanocytes such as bFGF and SCF, or to those that inhibit melanocytes such as IL-6 andTNF-α. SCF is an essential factor for melanocyte survival (Tarlé et al., 2014).
Vitiligo affects approximately 1% of the world’s population. Both adults and children are affected with no predilection for sex or ethnicity. The average age at onset lies around the second to the third decade of life (Alikhan et al., 2011).
Interleukin-19 is a cytokine that belongs to the IL-
10 family of cytokines along with several other interleukins including IL-10, IL-20, IL-22, IL24, IL-26, and several virus-encoded cytokines. It signals through the same cell surface receptor (IL-20R) that is used by IL-20 and IL-24 (Ebrahim, Mustafa, & Abd-Elghany, 2020).
So this study aimed toevaluate the serum level of IL-19 in patients with Vitiligo to assess its role in Vitiligo.
In the current study, mean ± SD of IL–19 in case group is 264.87 ± 764.29, and in control group is 1188.96 ± 1630.04, and there is high statistical significant difference between two groups as regard IL19 level which is lower in case group (p<0.001).
In this study, validity analysis of IL-19 for diagnosis and discrimination of vitiligo at cut off level lower than 25 showed AUC of 0.808 with 83%% sensitivity and 85% specificity.
Despite the high expression levels of IL-19 receptor in a variety of non-immune cells, no effects of IL-19 on these cells has been described so far. The currently available data suggest a pivotal role of IL-19 in the immune response, but the biological role of this cytokine should be further evaluated in additional studies(Gallagher et al., 2006).