Reduction of skin-homing cytotoxic T cells (CD8+ -CLA+) in patients with vitiligo

Background: Vitiligo is a frequently acquired, hereditary disease, characterized by achromic macules due to the absence of melanocytes. In contrast with earlier studies, in which the main pathogenic role was attributed to anti‐melanocyte antibodies, recent papers have emphasized a role for CD8⁺ cytotoxic T lymphocytes in melanocyte destruction. Fifteen percent of peripheral T cell express cutaneous lymphocyte‐associated antigen (CLA), responsible for skin‐homing T cell. Phototherapy is used to treat patients with generalized vitiligo and it has been shown to interfere with CLA⁺ T cells in other skin diseases. Objective: To describe peripheral blood T cell subpopulations' frequency and ability to express the skin‐homing molecule (CLA) in patients with non‐segmental vitiligo, before and after photochemotherapy (PUVA). Patients and Methods: Twenty‐two patients with generalized and active spreading vitiligo were submitted to 30 PUVA‐8MOP sessions. Lymphocyte immunophenotyping was performed by flow cytometry using anti‐CD3, anti‐CD8 and anti‐CLA monoclonal antibodies. Fifteen healthy volunteers, sex‐ and age‐matched, were included as a control group. Results: CD8⁺–CLA⁺ T cells were significantly reduced in number in untreated vitiligo patients (P=0.008) when compared with control individuals, albeit with a more intense CLA expression (P=0.028). These findings were not altered after PUVA. No significant difference was noticed in CD4/CD8 ratios nor in CD4–CLA⁺ T cell numbers between vitiligo patients and controls, both before and after PUVA. Conclusions: CD8–CLA⁺ T cells are reduced in peripheral blood of patients with non‐segmental vitiligo. This finding may be related to the previously reported increase of CD8⁺ cells in both lesions and perilesional skin of these patients.     

Evaluation of activatory and inhibitory natural killer cell receptors in non-segmental vitiligo: a flow cytometric study

Background Recent observations established the role of altered cellular immunity and autoimmune hypothesis in the pathogenesis of vitiligo. There have been several reports discussing T‐cell and natural killer (NK) cell populations, but NK cell receptors were not evaluated in vitiligo. Objective The purpose of this investigation was to assess the role of T and NK cells as well as activatory and inhibitory NK cell receptor alterations in the pathogenesis of vitiligo and whether any aberrations were correlated with clinical findings of the disease. Patients/methods Fifty‐three patients with non‐segmental vitiligo and 45 age‐ and sex‐matched healthy controls were enrolled in the study. The percentages of lymphocytes, granulocytes, monocytes and CD3, CD4, CD8, CD14, CD16, CD56, CD45, CD45RA, CD54RO, CD28, CD80, CD94, CD158a, KIR3DL‐1 receptors as well as CD94, CD158a, KIR3DL‐1 receptors on CD16⁺ cells were detected by using flow cytometry. The patient and control groups were compared in terms of the results of flow cytometric analysis, and the results were assessed regarding the type and activity of vitiligo. Results The percentages of CD16⁺CD56⁺, CD3⁺CD16⁺CD56⁺, CD8⁺ and CD45RO⁺ cells were significantly increased in vitiligo group compared with the controls. No difference was detected between the patients and control groups in percentages of CD3⁺, CD4⁺, CD3^?CD16⁺CD56⁺, CD28⁺, CD45⁺, CD45RA⁺, CD94⁺, CD158a⁺ and KIR3DL‐1⁺ cells. The percentage of CD16⁺CD158a⁺ cells was significantly decreased in a randomized selected group of vitiligo patients. There were no differences in percentage expression of studied cell surface antigens between patients in the active or stable period. CD3⁺ cells were significantly increased in generalized form, and CD45RO⁺ cells were significantly increased in acral/acrofacial form when compared with the other types of vitiligo. Conclusions These results indicate further evidence for T and NK cell abnormalities in non‐segmental vitiligo. The present data show that NK cell activation may be responsible in the pathogenesis of vitiligo in conformity with decreased inhibitory and increased activatory NK cell receptors.     

表没食子儿茶素没食子酸酯和补骨脂对莫诺苯宗诱导白癜风样小鼠的影响

目的 探讨表没食子儿茶素没食子酸酯（EGCG）和补骨脂对莫诺苯宗诱导的白癜风样小鼠的影响。 方法 C57BL/6小鼠40只,脱去背部2 cm × 2 cm区域毛,随机分为4组,每组10只。阴性对照组涂抹凡士林乳膏;模型组涂抹40%莫诺苯宗乳膏;EGCG组先后涂抹5% EGCG、40%莫诺苯宗乳膏;补骨脂组先后涂抹7%补骨脂、40%莫诺苯宗乳膏。观察小鼠皮肤和毛发脱色情况,组织病理检查观察淋巴细胞浸润,免疫荧光检测CD8+ T细胞表达量。 结果 阴性对照组小鼠皮肤和毛发无脱色现象。模型组小鼠在用药部位及非用药部位均有脱色现象,EGCG组和补骨脂组小鼠用药部位全部出现脱色,用药部位出现脱色斑的平均时间分别为16.7、29.3和19.9 d,脱色面积指数分别为4.00 ± 0.00、2.11 ± 0.54、2.84 ± 0.79,EGCG组、补骨脂组和模型组之间脱色面积指数差异有统计学意义（F = 14.17,P < 0.05）,EGCG组和补骨脂组分别与模型组比较,脱色面积指数差异均有统计学意义（均P < 0.05）;同时,EGCG组和补骨脂组非用药部位的脱色面积指数差异同样有统计学意义（P < 0.05）。EGCG组和补骨脂组CD8+ T细胞表达量均低于模型组,EGCG组和补骨脂组差异亦有统计学意义（P < 0.05）。 结论 EGCG和补骨脂对莫诺苯宗诱导的小鼠皮肤和毛发脱色均有干预作用,EGCG的干预作用比补骨脂的干预作用强,该动物模型与人类白癜风具有极高相似性。     

局部针刺对莫诺苯宗诱导C57BL/6小鼠白癜风样模型的影响

【摘要】 目的 探讨外伤对莫诺苯宗诱导白癜风小鼠脱色的影响。 方法 将40只C57BL/6小鼠随机分为对照组、模型组、针刺组和针刺配合莫诺苯宗组4个组,每组10只。模型组应用40%莫诺苯宗乳膏诱导C57BL/6小鼠脱色,建立白癜风动物模型;针刺配合莫诺苯宗组通过针刺配合40%莫诺苯宗乳膏的方法,研究针刺对小鼠脱色的影响。实验过程中肉眼观察毛发颜色以及共聚焦激光扫描显微镜（RCM）观察皮肤脱色。实验结束后麻醉小鼠,取非用药部位脱色皮肤行组织学检查,HE染色检测淋巴细胞浸润情况,免疫荧光染色检测CD8+ T细胞表达。 结果 模型组小鼠在用药部位及非用药部位均有不同程度脱色。针刺配合莫诺苯宗组小鼠同样具有以上特点,且其脱色出现时间早,面积大并稳定。实验第65天,模型组和针刺配合莫诺苯宗组用药部位的脱色面积指数分别为3.45 ± 0.17和3.90 ± 0.25,两组比较差异有统计学意义,t = 7.433,P < 0.05;非用药部位分别为1.90 ± 0.12和2.85 ± 0.27,两组比较差异有统计学意义,t = 7.529,P < 0.05。免疫荧光显示非用药部位脱色区CD8+ T细胞荧光强度模型组为175.528 ± 10.711,针刺配合莫诺苯宗组为645.928 ± 12.652,两者比较差异有统计学意义,t = 8.105,P < 0.05。针刺配合莫诺苯宗组在非用药部位脱色斑局部淋巴细胞和CD8+ T细胞浸润更明显。 结论 局部皮肤屏障破坏可以促进莫诺苯宗诱导的白癜风小鼠脱色。     

Expression analysis of PD‐1 and Tim‐3 immune checkpoint receptors in patients with vitiligo; positive association with disease activity

The contribution of immune checkpoint receptors in the immunopathogenesis of various autoimmune diseases has been addressed in previous reports. In this study,  the expression profile of T‐cell immunoglobulin and mucin‐domain containing‐3 (Tim‐3) and programmed cell death‐1 (PD‐1) checkpoint molecules was investigated in CD8⁺ T cells of Vitiligo patients. The association of Tim‐3 and PD‐1 expression with disease activity was also explored. The frequency of Tim‐3⁺/PD‐1⁺/CD8⁺ T cells in 30 patients with vitiligo and 30 sex‐ and age‐matched controls was determined by flow cytometry. CD8⁺ T cells were then positively isolated by magnetic beads, and the mRNA expression of PD‐1 and Tim‐3 was determined by TaqMan‐based real‐time PCR. To measure the cytokines production, PBMCs were stimulated with PMA/ionomycin and concentrations of IL‐4, IFN‐γ and TNF‐α were measured in culture supernatants by ELISA. Disease activity of patients with vitiligo was determined using the Vitiligo Area Severity Index. Patients with vitiligo have significantly shown more expression of Tim‐3 and PD‐1 on their CD8⁺ T cells compared with controls. Expression analysis of Tim‐3 mRNA, but not PD‐1, confirmed the results obtained from flow cytometry. While the production levels of TNF‐α and IFN‐γ were found higher by patients with vitiligo, IL‐4 production was lower in patients compared with controls. A direct association was observed between the Tim‐3 and PD‐1 expression and also the production of pro‐inflammatory cytokines with disease activity of patients with vitiligo. Our results indicate that Tim‐3 and PD‐1 are involved in immune dysregulation mechanisms of CD8⁺ T cells in vitiligo and may introduce as potential biomarkers for disease progression and targeted immunotherapy.     

Density and proportions of the epidermal T cell population in human sun-exposed skin differ from those in sun-protected skin: preliminary immunohistochemical study

Epidermal T cells, which are found in clinically normal human skin, show topographic differences in density and proportions; however, the mechanisms and the biological consequences of such differences are still unknown. In a previous work, we showed that epidermal T cells are altered in number and composition after a single exposure to solar-simulated radiation (SSR). The purposes of the present investigation were, first, to compare the density of epidermal T cells and the proportion of T cell subpopulations in habitually sun-exposed versus sun-protected sites; second, to determine the effects of repetitive exposures to SSR on the latter cell populations. Biopsies from habitually sun-exposed, sun-protected and solar-simulated-exposed skin of 28 healthy volunteers were taken and immunohistochemistry was performed on cryostat sections. Compared with sun-protected sites, epidermal CD3⁺ T cell numbers of habitually sun-exposed sites were significantly lower. Double staining showed that the number of CD3⁺CD8⁺ T cells was significantly lower in sun-exposed than in sun-protected skin, whereas the numbers of CD3⁺CD4⁺ T cells were similar in both sites. Therefore, the CD4/CD8 ratio was markedly higher in sun-exposed compared to sun-protected sites. Moreover, repeated exposures of sun-protected skin to SSR induced a significant reduction in number of epidermal CD3⁺ T cells. The mean number of epidermal CD3⁺CD8⁺ double stained cells significantly decreased after such exposures, while the epidermal CD3⁺CD4⁺ T cell subpopulation was not significantly changed. In conclusion, both chronically sun-exposed skin and repeatedly SSR-exposed skin show a decrease in density of epidermal CD3⁺ and CD3⁺CD8⁺ T cells. We hypothesize that such sun-induced changes may weaken the immunosurveillance capacity of the skin and therefore increase the occurrence of skin cancer.     

CD8+ lineage dendritic cells determine adaptive immune responses to inflammasome activation upon sterile skin injury

The molecular links between sterile inflammation and induction of adaptive immunity have not been fully identified. Here, we examine how damage‐associated molecular patterns (DAMPs), as opposed to pathogen‐associated molecules (PAMPs), regulate the immune response to non–self‐antigens presented at the site of a physical injury. Heat applied briefly to the skin invokes sterile inflammation, characterized by local cell death and caspase‐1 activation without demonstrably disrupting skin integrity. Co‐delivery of ovalbumin (OVA) with heat injury induces OVA‐specific CD8⁺ T‐cell responses, and this is dependent on caspase‐1 activation and MyD88 signalling. Using Id2flox/flox‐CD11cCre+ mice, we demonstrate that CD8⁺ lineage DCs are required to induce OVA‐specific CD8⁺ T‐cell responses following heat injury. Consistent with this observation, intradermal administration of CD8⁺ lineage DCs but not CD11b⁺ lineage DCs restores priming of CD8⁺ T‐cell responses in Casp‐1^?/? mice. Thus, we conclude that a sterile injury induces CD8⁺ T‐cell immune responses to local antigen through caspase‐1 activation and requires CD8⁺ lineage DCs, a finding of significance for immunotherapy and for the pathogenesis of autoimmunity.     

Role of macrophage infiltration in successful repigmentation in a new periphery‐spreading vitiligo lesion in a male Japanese patient

Vitiligo is an acquired disorder in which depigmented macules result from mostly autoimmune loss of melanocytes. The initiating process in vitiligo has still been uncertain. Here, we report the case of a 19‐year‐old man with undetermined/unclassified vitiligo with a new periphery‐spreading vitiligo lesion on the right dorsal hand after rigorous sun exposure. Histopathological evaluation showed noticeable infiltration of CD68⁺ macrophages, moderate infiltration of CD3⁺ T cells, little infiltration of CD8⁺ T cells and CD11c⁺ myeloid dendritic cells, HMB45/CD11c double‐positive cells, and Melan‐A/MART1⁺ deposits in the dermis. We surmised that melanocyte‐derived deposits were mostly phagocytosed by CD68⁺ macrophages and were faintly phagocytosed by CD11c⁺ myeloid dendritic cells, referring distribution of CD68⁺ mononuclear cells and melanocyte biomarkers. Complete repigmentation was achieved following topical application of hydrocortisone butyrate propionate 0.1% ointment. We summarize that prompt clearance of debris by macrophages would be essential to an excellent prognosis of complete repigmentation.     

Serum miRNA expression profiles change in autoimmune vitiligo in mice

It is widely believed that non‐segmental vitiligo results from the autoimmune destruction of melanocytes. MicroRNAs (miRNAs), a class of small non‐coding RNAs that negatively regulate gene expression, are involved in the immune cell development and function and regulate the development of autoimmune diseases. Recent studies demonstrate that functional miRNAs can be detected in the serum and serve as biomarkers of various diseases. In the present study, we used a mouse autoimmune vitiligo model, in which melanocyte autoreactive CD4⁺ T cells were adoptively transferred into Rag1^?/? host mice. Serum miRNA expression was profiled in vitiligo developed mice and control mice using TaqMan RT‐PCR arrays. We have found that the expressions of 20 serum miRNAs were changed in vitiligo mice compared to control mice. Three increased miRNAs, miR‐146a, miR‐191, and miR‐342‐3p, were further confirmed by a single TaqMan RT‐PCR. Our findings suggest that miRNAs may be involved in vitiligo development and serum miRNAs could serve as serum biomarkers for vitiligo in mice.     

Levels of TGF-β<Subscript>1</Subscript> in serum and culture supernatants of CD4<Superscript>+</Superscript>CD25<Superscript>+</Superscript> T cells from patients with non-segmental vitiligo

Compelling evidences support an autoimmune basis of non-segmental vitiligo, and dysregulation of CD4⁺CD25⁺ regulatory T cell (Treg) is assumed to contribute to the pathogenesis of vitiligo. Serum levels of transforming growth factor-β (TGF-β), an important immunoregulatory cytokine produced by Treg cells, has been reported significantly decreased in patients with vitiligo. However, relation between the decrease in TGF-β and the dysfunction of Treg cells in pathogenesis of vitiligo was still undemonstrated. To further reveal the role of TGF-β in vitiligo, 46 patients with non-segmental vitiligo and 25 age- and sex-matched healthy control subjects were enrolled in the study. CD4⁺CD25⁺ T cells isolated from peripheral venous blood with a CD4⁺CD25⁺ regulatory T cell isolation kit were cultured with or without anti-CD3 mAbs and anti-CD28 mAbs for 4 days. The TGF-β1 levels in serum and culture supernatants were detected by enzyme-linked immunosorbent assay in both groups. We have found that the TGF-β1 levels both in serum and culture supernatants in the presence of anti-CD3 mAbs and anti-CD28 mAbs were decreased in the active vitiligo group when compared with the control group or stable vitiligo group, and were negatively correlated with the percentage of involved body area. These results suggested that TGF-β may play a role in the pathogenesis of non-segmental vitiligo related to the suppressive function of Tregs.     

Characterization of the T cell response in allergic contact dermatitis caused by corticosteroids

Background Delayed allergic hypersensitivity reactions have classically been described as type IV reactions, which are caused by T cells; however, the respective roles of CD4⁺ and CD8⁺ cells are yet to be defined. A central role for CD8⁺ cytotoxic T cells as effector cells has been suggested. Objectives To determine the type of T cell involved in corticosteroid allergy. Methods We analysed the kinetics of T cell recruitment and the cytokine production profile in positive patch tests of 27 corticosteroid‐sensitized patients, as compared with control sites and control subjects. Skin biopsies, collected at 8, 24 and 48 hr following drug application, were embedded in paraffin for histological and immunohistological staining, and, in some cases, also deep‐frozen for gene expression analyses. Results CD3⁺ T cells were rapidly recruited in concert with the positivity of the patch test sites. High levels of interleukin (IL)‐4, IL‐5 and, to a lesser extent, interferon‐γ suggested that both Th2 and Th1 cytokines were implicated. IL‐4 was also produced by γδ T cell receptor (TCR) lymphocytes. Conclusions This study showed that, in allergic contact dermatitis caused by corticosteroids, the inflammatory infiltrate is composed of CD3⁺ T cells with a predominant Th2 cytokine profile, among which IL‐4 is also produced by γδ TCR lymphocytes.     

Role of chemokines and the corresponding receptors in vitiligo: A pilot study

To determine the levels and sources of chemokines in the serum and epidermis of vitiligo patients, we examined 80 active patients, 80 stable patients and 40 healthy controls. First, the serum levels of candidate chemokines were measured by Luminex assay, and levels of CCR5, CXCR1 and CXCR3 were measured in peripheral mononuclear cells (PMBC) by flow cytometry. Then, the local epidermis levels of elevated chemokines in vitiligo were tested by Luminex. Finally, the mRNA and protein expression levels of elevated chemokines in HaCaT cells stimulated with interferon (IFN)‐γ or tumor necrosis factor (TNF)‐α were tested by quantitative real‐time polymerase chain reaction and Luminex. The serum levels of CCL5, CXCL8 and CXCL10 in active vitiligo were significantly elevated compared with those in stable vitiligo patients. Furthermore, the levels of CCL3 and CCL4 had weak and positive correlations with the Vitiligo Area Scoring Index. In the peripheral blood of active vitiligo patients, the percentages of CD3⁺CD8⁺CCR5⁺ and CD3⁺CD8⁺CXCR3⁺ T cells were significantly increased compared with those in stable vitiligo and healthy controls. In the epidermis of lesions, the expression levels of CCL5 and CXCL10 in active vitiligo were significantly increased. In addition, the mRNA and protein levels of CCL5, CXCL8 and CXCL10 were significantly elevated in HaCaT cells after stimulation with TNF‐α or IFN‐γ. The CCR5/CCL5 and CXCR3/CXCL10 axes may play an important role in the progression and maintenance of vitiligo. Moreover, keratinocytes stimulated with TNF‐α and IFN‐γ may be a primary source of CCL5 and CXCL10.     

CD4+ T cells producing interleukin (IL)‐17, IL‐22 and interferon‐γ are major effector T cells in nickel allergy

Background It has been suggested that interleukin (IL)‐17 and IL‐22 play important roles in the elicitation of human allergic contact dermatitis; however, the frequencies of T cell subtypes producing IL‐17 and IL‐22 in human allergic contact dermatitis are unknown. Objectives To determine the frequencies of CD4⁺, CD8⁺ and γδ T cells producing IL‐17, IL‐22 and interferon (IFN)‐γ in the blood and skin from nickel‐allergic patients. Patients/materials/methods Blood samples were collected from 14 patients and 17 controls, and analysed by flow cytometry. Biopsies were taken from 5 patients and 6 controls, and analysed by immunohistochemistry and flow cytometry of skin lymphocytes. Results We found an increased frequency of γδ T cells in the blood, but no differences in the distribution of cytokine‐producing CLA⁺ T cell subtypes in nickel‐allergic patients as compared with controls. In nickel‐allergic patients, there was massive cellular infiltration dominated by CD4⁺ T cells producing IL‐17, IL‐22 and IFN‐γ in nickel‐challenged skin but not in vehicle‐challenged skin. Conclusion CD4⁺ T cells producing IL‐17, IL‐22 and IFN‐γ are important effector cells in the eczematous reactions of nickel‐induced allergic contact dermatitis in humans.     

Osteopontin deficiency affects imiquimod‐induced psoriasis‐like murine skin inflammation and lymphocyte distribution in skin,draining lymph nodes and spleen

Osteopontin (OPN) that enhances autoimmunity is expressed in psoriasis lesions; however, its functions in psoriatic inflammation are unknown. We investigated the role of OPN in OPN deficient mice (OPN?/?) by inducing psoriasis‐like inflammation through skin application of imiquimod (IMQ). OPN?/? mice treated with IMQ showed delayed onset ear swelling and attracted less inflammatory cells to the skin. IMQ‐induced lymph node swelling was reduced in the absence of OPN, and IMQ‐mediated expansion of B cells was inhibited. Further, reduction of CD4⁺ T‐cell numbers by IMQ in lymph nodes was suppressed in OPN?/? mice, with an increase in the CD4/CD8 ratio. A comparable pattern was found in spleen. Importantly, IMQ‐induced IL‐17 and IL‐4 expression by CD4⁺ lymph node T cells was reduced in OPN?/? mice. In conclusion, OPN may modulate psoriasis‐like inflammation through altering lymphocyte distribution in skin and draining lymph nodes and by inducing IL‐17 expression of inflammatory T cells.     

CpGB DNA activates dermal macrophages and specifically recruits inflammatory monocytes into the skin

Toll‐like receptor 9 (TLR9) drives innate immune responses after recognition of foreign or endogenous DNA containing unmethylated CpG motifs. DNA‐mediated TLR9 activation is highly implicated in the pathogenesis of several autoimmune skin diseases, yet its contribution to the inflammation seen in these diseases remains unclear. In this study, TLR9 ligand, CpGB DNA, was administered to mice via a subcutaneous osmotic pump with treatment lasting 1 or 4 weeks. Gene expression and immunofluorescence analyses were used to determine chemokine expression and cell recruitment in the skin surrounding the pump outlet. CpGB DNA skin treatment dramatically induced a marked influx of CD11b⁺ F4/80⁺ macrophages, increasing over 4 weeks of treatment, and induction of IFNγ and TNFα expression. Chemokines, CCL2, CCL4, CCL5, CXCL9 and CXCL10, were highly induced in CpGB DNA‐treated skin, although abrogation of these signalling pathways individually did not alter macrophage accumulation. Flow cytometry analysis showed that TLR9 activation in the skin increased circulating CD11b⁺ CD115⁺ Ly6C^hi inflammatory monocytes following 1 week of CpGB DNA treatment. Additionally, skin‐resident CD11b⁺ cells were found to initially take up subcutaneous CpGB DNA and propagate the subsequent immune response. Using diphtheria toxin‐induced monocyte depletion mouse model, gene expression analysis demonstrated that CD11b+ cells are responsible for the CpGB DNA‐induced cytokine and chemokine response. Overall, these data demonstrate that chronic TLR9 activation induces a specific inflammatory response, ultimately leading to a striking and selective accumulation of macrophages in the skin.     

Regulation of nickel-induced T-cell responsiveness by CD4+CD25+ cells in contact allergic patients and healthy individuals

In this study, we investigated the capacity of CD4⁺CD25⁺ regulatory T cells to suppress nickel‐specific effector T cells, both in nickel‐allergic patients and healthy controls. CD4⁺ cells isolated from allergic patients showed an increased proliferative response to nickel, whereas CD4⁺ cells from negative controls did not respond to allergen. When CD4⁺CD25⁺ cells were depleted, nickel‐specific responsiveness was strongly increased both in allergic and in non‐allergic individuals, with the most pronounced effect in allergic patients. These regulatory T cells were anergic to nickel but inhibited nickel‐specific CD4⁺CD25^– effector T cells in coculture experiments. CD4⁺CD25⁺ cells from nickel‐allergic patients showed only a limited capacity to suppress effector T‐cell responsiveness, because an increased nickel reactivity could still be detected in these cocultures. None of the isolated CD4⁺CD25⁺ cells, either isolated from healthy controls or allergic patients, produced IL‐10 in response to nickel. Overall, these results support the view that CD4⁺CD25⁺ cells can control the activation of nickel‐specific effector T cells in non‐allergic individuals, whereas this regulatory capacity is impaired in allergic patients. To investigate the presence of allergen‐specific regulatory T cells in truly naïve, non‐sensitized individuals, T‐cell reactivity should also be studied with non‐environmental contact allergens, such as para‐phenylenediamine.     

Depigmentation therapy

ABSTRACT: Depigmentation therapy is a treatment option for patients with widespread, treatment-resistant vitiligo. The most commonly employed technique is the application of monobenzylether of hydroquinone (MBEH), also known as monobenzone, to areas with residual pigment. Prior to instituting therapy, the patient must be aware of the cost, treatment time course, risk of distant sites of depigmentation, probable permanency of depigmentation, side effects such as contact dermatitis, and the potential for repigmentation via follicular melanocytes. The social ramifications of depigmentation therapy also must be discussed, especially for patients with skin types IV and V. The sequential use of 4-methoxyphenol and Q-switched ruby laser also has been reported as a successful form of depigmentation therapy.