Función efectora de linfocitos T CLA+ sobre queratinocitos autólogos en psoriasis

BackgroundCutaneous lymphocyte antigen (CLA) is expressed by a subgroup of memory T cells that exhibit skin homing and are implicated in cutaneous T-cell-mediated diseases.Material and methodsExpression of genes associated with psoriasis was analyzed in keratinocytes taken from patients and healthy individuals and cultured under different conditions, including activation using supernatants from CLA⁺ T lymphocytes activated with anti-CD3 and anti-CD28 antibodies.ResultsKeratinocytes from psoriasis patients activated by CLA⁺ T lymphocytes expressed higher levels of interferon-inducible protein 10, HLA-DR, intercellular cell adhesion molecule 1, and inducible nitric oxide synthase.ConclusionsOur results suggest that we have developed an in vitro model that will allow analysis of the effector role of CLA⁺ T lymphocytes on keratinocytes in psoriasis. This model may allow the identification of genes involved in the pathology of psoriasis through induction by CLA⁺ T lymphocytes.     

A mouse model of vitiligo induced by monobenzone

The paucity of vitiligo animal models limits the understanding of vitiligo pathogenesis and the development of therapies for the skin disorder. In this study, we developed a new mouse model of vitiligo by topically applying the skin‐depigmenting agent monobenzone on mice. We demonstrated that monobenzone‐induced skin depigmentation on the non‐exposed sites and that the severity of lesions depended on drug dosage. The result of the histological examination of the depigmented skin indicated loss of epidermal melanocytes and perilesional accumulation of CD8⁺ T cells. Furthermore, the monobenzone‐induced depigmentation of the Rag1 gene knockout did not appear on the non‐exposed sites, supporting the involvement of infiltrating CD8⁺ T cells in melanocyte destruction. Resemblance in histological characteristics and pathogenesis between monobenzone‐induced depigmentation and active human vitiligo suggests good potential of our mouse model for use in vitiligo research.     

1,24‐Dihydroxyvitamin D3 (tacalcitol) prevents skin T‐cell infiltration

Background 1,24‐Dihydroxyvitamin D₃ (tacalcitol), a vitamin D₃ compound, has been used to treat T cell‐mediated inflammatory skin diseases such as psoriasis, prurigo and vitiligo. The best‐known mechanism of action of this compound is inhibition of the abnormal proliferation of keratinocytes and subsequent maturation; however, its effects on skin T‐cell recruitment have not yet been evaluated. Cutaneous lymphocyte‐associated antigen (CLA), a surface glycoprotein expressed on T cells, plays a critical role in skin T‐cell infiltration. We recently reported that 1,25‐dihydroxyvitamin D₃ inhibits skin infiltration of CD4+ T cells by suppressing CLA expression on T cells. Objectives In this study, we investigated the effect of tacalcitol on CLA epitope decoration and on the levels of gut or lymph node homing receptor expression in human T cells. Methods We cultured human T cells with tacalcitol and analysed the effect on CLA expression and skin‐homing ability, and evaluated glycosyltransferase mRNAs. We also performed an in vivo study using an antigen‐dependent delayed‐type hypersensitivity (DTH) mouse model and investigated the effect of tacalcitol on skin‐infiltrating CD4+ T cells. Results Tacalcitol downregulated the expression of CLA and, in parallel, the E‐ and P‐selectin ligand function; however, it exerted no effect on other homing receptors. Subcutaneously and intraperitoneally administered tacalcitol downregulated skin infiltration of effector CD4+ T cells in an in vivo DTH mouse model. Conclusions These findings suggest that tacalcitol reduces skin inflammation by partially downregulating CLA expression levels.     

8-Methoxypsoralen plus UVA treatment increases the proportion of CLA+ CD25+ CD4+ T cells in lymph nodes of K5.hTGFβ1 transgenic mice

Abstract: 8‐Methoxypsoralen plus UVA (PUVA) photochemotherapy is an effective treatment for many skin diseases including psoriasis. However, its exact mechanism of therapeutic action is incompletely understood. Previously, in K5.hTGFβ1 transgenic psoriatic mice, we found that PUVA induces Foxp3+ CD25+ CD4+ regulatory T cells in both lymph node and spleen. Now, in the same model, we investigated whether cutaneous lymphocyte‐associated antigen (CLA) mediates PUVA’s effect on homing of CD25+ CD4+ T cells to the lymph nodes of K5.hTGFβ1 transgenic mice. We found that a low dose of topical PUVA maximally increased the proportion of CLA + CD25+ CD4 + T cells in the lymph nodes by up to 8‐fold. We also observed an increased number of Foxp3+ CD25+ T cells in the skin of the mice after PUVA treatment. Together, these findings suggest that PUVA affects the homing of regulatory T cells.     

Regulatory T cells from active non-segmental vitiligo exhibit lower suppressive ability on CD8<Superscript>+</Superscript>CLA<Superscript>+</Superscript> T cells

Background

Recent studies have shown that vitiligo is a T-cell mediated autoimmune disease. Skin-homing cytotoxic T lymphocytes expressing cutaneous lymphocyte-associated antigen (CLA) have been suggested to be responsible for the destruction of melanocytes in vitiligo. An aberration in the suppressive function of regulatory T cells (Tregs) has been reported in vitiligo patients. However, whether the weakened suppressive ability of the Tregs contributes to hyper-activated skin homing CD8⁺CLA⁺ T cells remains to be determined.

Objectives

To investigate the inhibition of circulating Tregs on the proliferation of autologous CD8⁺CLA⁺ T cells in non-segmental vitiligo patients.

Methods

CD8⁺CLA⁺ T cells and Tregs were obtained from the peripheral blood of 13 non-segmental vitiligo patients and 7 controls. The proliferative responses of CD8⁺CLA⁺ T cells were assessed in the absence or presence of autologous Tregs, and the levels of Transforming Growth Factor β1(TGF-β1) and IL-10 in culture supernatants were detected by enzyme-linked immunosorbent assay.

Results

The proliferative responses of circulating CD8⁺CLA⁺ T cells in the presence of Tregs were significantly higher in the active vitiligo than in the stable vitiligo and control groups. Tregs from active vitiligo patients exhibited a lower inhibitory effect on proliferation of CD8⁺CLA⁺ T cells. The levels of TGF-β1 produced by Tregs were significantly lower in active vitiligo than other groups and anti-TGF-β1 antibodies could abrogate the suppressive function of Tregs.

Conclusions

The functional activity of Tregs is compromised in active vitiligo patients. TGF-β1 plays an important role in the autoimmune mechanism of the disease.

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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.     

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.     

Immunological effects of stress in psoriasis

Background Psychological stress causes phenotypic changes in circulating lymphocytes and is regarded as an important trigger of the Th1‐polarized inflammatory skin disease psoriasis. Objective To study the effects of psychological stress on immunological parameters, i.e. membrane molecules relevant to the pathophysiology of psoriasis, especially cutaneous lymphocyte‐associated antigens (CLA) involved in T and natural killer (NK) cells homing in on the skin. Methods The severity of psoriasis was assessed in patients using the Psoriasis Area and Severity Index. Patients with psoriasis (n = 15) and healthy volunteers (n = 15) were exposed to brief psychological stress in the laboratory. In vitro analyses were conducted 1 h before, immediately following and 1 h after stress exposure. Peripheral T‐ and NK‐cell subsets including CD8+ T lymphocytes, CLA+ lymphocytes and lymphocyte function‐associated antigen type 1 (LFA‐1)+ lymphocytes were analysed by flow cytometry. Results We found a significant stress‐induced increase of CD3+ T lymphocytes in patients with psoriasis only. Analyses of T‐cell subsets revealed that this increase was observable for cytotoxic CD8+ T lymphocytes and CLA+ CD3+ lymphocytes. The total number of circulating NK cells (CD16+, CD56+) increased immediately after stress in both groups whereas only patients with psoriasis showed a significant increase in CLA+ NK cells. Conclusions A higher stress‐induced increase of CLA+ T and CLA+ NK cells in the circulation of patients with psoriasis might point to an increased ability of T and NK cells in the presence of psoriasis to home in on the skin during mental stress. Further studies are needed to verify these relationships in more detail and to investigate the time point at which these cells accumulate within lesional skin, and whether or not psychotherapy improves the quality of life of patients with psoriasis and influences stress‐dependent parameters.     

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.     

Induction of cutaneous lymphocyte-associated antigen expression by group A streptococcal antigens in psoriasis

β2 expression and proliferation to GAS studied. Mean CLA expression by freshly isolated T cells was almost identical in the three groups. After culture with GAS, T cells from the psoriatic patients and control groups showed a significant increase in mean percentage CLA ⁺ expression compared to medium ( P < 0.002, P < 0.05, respectively). This induction was inhibited by the addition of anti-IL-12 antibody. However, in psoriatic patients, but not in controls, the GAS-induced increase was significantly greater than that of C. albicans ( P < 0.002) and was accompanied by a decrease in T cells positive for the peripheral lymph node homing receptor, L-selectin ( P < 0.05). The percentage of Vβ2 ⁺ T cells was markedly higher in the CLA ⁺ than in the CLA ^– T-cell subset in psoriatic patients ( P < 0.01) and controls; both subsets proliferated to GAS, in each group. These findings suggest a differential modulation of specific tissue homing receptors on T cells by GAS in psoriasis. Received: 7 July 1997     

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.     

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.     

Development and characterization of a monoclonal antibody specific for fucosyltransferase VII (Fuc-TVII): discordant expression of CLA and Fuc-TVII in peripheral CD4+ and CD8+ T cells

Although cutaneous lymphocyte-associated antigen (CLA) is thought to be specifically expressed on skin "homing" T cells, it has become clear that CLA is not directly involved in binding to E-selectin but represents an excellent marker for high levels of fucosyltransferase VII (Fuc-TVII): Fuc-TVII can regulate the ability of T cells to migrate into the skin by generating a binding site for E-selectin. In this study, by using a novel monoclonal antibody for Fuc-TVII, we investigated whether expression of Fuc-TVII could be selectively detected in various CLA+ cell lines and peripheral blood T cells. Fuc-TVII was readily detected in the cytoplasm, but not in the membrane, of CLA+ cell lines. Cytoplasmic Fuc-TVII expression was also detectable in both CD4+ and CD8+ T cells purified from peripheral blood mononuclear cells. Nevertheless, there were significant numbers of CLA-expressing CD4+ or CD8+ T cells that did not coexpress Fuc-TVII, and vice versa: either the CD4+ or the CD8+ T cell population consisted of a variable ratio of CLA+ Fuc-TVII+, CLA+ Fuc-TVII-, and CLA- Fuc-TVII+ cells; and CLA+ Fuc-TVII- cells were the most abundantly identifiable phenotype in peripheral blood CD4+ and CD8+ T cells. Thus, according to their expression pattern, skin "homing" T cells can be subdivided into at least three populations, CLA+ Fuc-TVII+, CLA+ Fuc-TVII-, and CLA- Fuc-TVII+ cells. Our study provides convincing evidence that skin "homing" T cells are phenotypically heterogenous and that Fuc-TVII expression, in combination with CLA expression, is a useful phenotypic marker for identifying skin "homing" T cells in mixed cell populations.     

The HECA-452 epitope is highly expressed on lymph cells derived from human skin

The cutaneous lymphocyte-associated antigen (CLA), recognized by the monoclonal antibody HECA-452, is a cell surface glycoprotein that binds specifically to E-selectin. CLA is present on most T cells at sites of cutaneous immune response and has been shown to be important in lymphocyte homing to the skin. It is expressed only by a minor subset of peripheral T cells and is absent on thymocytes. We have analysed (using a FACScan flow cytometer) the expression of CLA on human lymph cells derived from normal skin, from ultraviolet (UV)-irradiated skin and from allergic contact dermatitis. Whereas in the peripheral blood CLA was expressed on < 20% of CD4 +, CD8 + and CD56 + cells (natural killer cells), > 60% of CD4 +, CD8 + and CD56 + cells isolated from skin-derived lymph expressed CLA. Furthermore, > 90% of CD1a + dendritic lymph cells were positive for CLA. UV irradiation of the skin and induction of an allergic contact dermatitis did not change CLA expression on lymph cells, although lymph flow and cell output increased. These results provide further evidence for an important role of CLA in cell homing to the skin.     

Papuloerythroderma‐like cutaneous involvement of a CD62L− subclone of T‐cell prolymphocytic leukemia

We report the case of an 88‐year‐old Japanese man with erythrodermic involvement of T‐cell prolymphocytic leukemia (T‐PLL). He had a history of pharyngeal diffuse large B‐cell lymphoma successfully treated with polychemotherapy including cyclophosphamide and epirubicin, 6 years before the current illness. He presented with numerous reddish, coalescing, flat‐topped papules on the trunk and extremities, sparing the skin folds of the abdomen, the features of which mimicked those of papuloerythroderma. Immunohistochemistry showed perivascular and epidermotropic infiltration of CD3⁺ CD4⁺ T cells in the cutaneous lesion. However, flow cytometric analysis revealed that the skin infiltrating T cells were negative for surface CD4, and that CD3⁺ CD4^? CD8^? cells made up 92% of the T‐cell fraction of peripheral blood. The circulating atypical T cells had a round or oval nucleus and prominent nucleoli, and the deletion of chromosomes 6q, 13 and 17. These cytological profiles were consistent with those of T‐PLL and distinct from those of Sézary cells. The same T‐cell clone was detected in the cutaneous lesion and peripheral blood, but the expression of CD62L was absent in the skin infiltrates and present in the circulating cells. No specific mutation was detected in STAT3 or STAT5B. Although low‐dose oral etoposide had a beneficial effect on the skin rash, a fatal crisis of marked leukocytosis (169 × 10³/μL) occurred 19 months after the illness onset. CD62L‐leukemic cells of T‐PLL may infiltrate the skin to form papuloerythroderma‐like cutaneous lesions.     

Acral lesions of vitiligo: why are they resistant to photochemotherapy?

Background Acral lesions of vitiligo are usually resistant to conventional lines of treatment as well as surgical interventions. Objective To clarify causes underlying resistance of acral lesions to pigmentation in vitiligo by studying some of the factors associated with mechanisms of repigmentation following photochemotherapy. Methods The study included twenty patients with active vitiligo. Skin biopsies were taken from lesional and perilesional skin of areas expected to respond (trunk and proximal limb) and skin of acral areas, before and after PUVA therapy. Sections were stained with H and E, Melan‐A, MHCII, CD1a, SCF and c‐kit protein. Results Before treatment acral areas showed significantly lower hair follicle density, melanocyte density, Langerhans cell (LC) density, epidermal MHCII expression, lesional SCF expression and perilesional c‐kit expression. Following treatment with PUVA in both non‐responsive acral and repigmenting non‐acral lesions identical immunohistochemical changes in the form of significant decrease in LC density, epidermal MHC‐II and SCF expression were observed. Conclusion The surprisingly similar histochemical changes in response to PUVA in acral and non‐acral lesions did not manifest with clinical repigmentation except in non‐acral ones. Factors such as inherent lower melanocyte density, lower melanocyte stem cell reservoirs and/or lower baseline epidermal stem cell factor may be considered as possible play makers in this respect.     

Bath psoralen+ultraviolet A photochemotherapy vs. narrow band‐ultraviolet B in psoriasis: a comparison of clinical outcome and effect on circulating T‐helper and T‐suppressor/cytotoxic cells

Background: Comparative success rates of bath psoralen+ultraviolet A (PUVA) and narrow band‐ultraviolet B (NB‐UVB) in psoriasis treatment are variably reported with no previous studies on the possible effect of bath PUVA on circulating CD4+ and CD8+ T cells. Objective: We aimed to compare the effect of bath PUVA and NB‐UVB clinically and on circulating T‐helper and T‐suppressor/cytotoxic cells in psoriasis. Patients and methods: Thirty‐four psoriatic patients divided into a bath PUVA‐treated group (18 patients) and a NB‐UVB‐treated group (16 patients) were compared regarding the disease severity by psoriasis area and severity index (PASI) score and percentage of circulating CD4+ and CD8+ T cells by flowcytometry before and after treatment. Results: After treatment, the bath PUVA group showed a significantly higher reduction of PASI score (85.44%) than the NB‐UVB group (58.72%). Mean peripheral CD4+ T‐cell percentage was significantly lower after [36.8; 95% confidence interval (CI) 33.80, 39.97] compared with before treatment (42.06; 95% CI 38.29, 45.83) (P<0.05) in the bath PUVA group while this difference was insignificant in the NB‐UVB group (P>0.05). Conclusion: Bath PUVA therapy is superior to NB‐UVB in the treatment of moderate and severe psoriasis with mild reversible side effects. Both modalities have a systemic effect decreasing peripheral CD4+ T cells, which is more with bath PUVA.     

Impaired T‐cell‐dependent protection against Leishmania major infection in HIV‐positive patients is associated with worsened disease outcome

Cutaneous leishmaniasis (CL) patients coinfected with HIV are known to show a more severe, prolonged course of disease; the immunological basis is not known. We now assessed clinical features, sera and skin biopsies of HIV⁺ and HIV^? patients with CL to identify drivers of increased susceptibility to Leishmania. CL lesion numbers, surface, and healing duration were significantly increased in HIV⁺ as compared to HIV^? patients (2.5, 14 and >4‐fold, respectively). Patients with HIV infection exhibited lower serum Leishmania‐specific IgG levels and decreased IL‐6 and IL‐8. Most importantly, dramatically decreased numbers of CD4⁺ T cells (approximately eightfold), but not CD8⁺ cells, together with fewer CXCR3⁺ Th1 cells, fewer Foxp3⁺ effector/regulatory T cells, and reduced levels of IFN‐γ expression were found in lesional skin. Our findings suggest that compromised CD4⁺ T‐cell responses may be responsible for worsened disease outcome leading to defects in parasite elimination in the absence of sufficient numbers of IFN‐γ‐producing Th1 cells.     

Possible role of superantigens in inducing autoimmunity in pemphigus patients

The diagnostic and pathological relevance of anti‐desmoglein autoantibodies in common forms of pemphigus has been well established, and T cells have been shown to play a role in the onset and progression of these diseases. The role of superantigens in provoking polyclonal activation of T cells with many different fine specificities, possibly including autoreactive T cells and T‐cell mediated autoantibody response, is unknown. Further, abnormal T‐cell function may lead to opportunistic infections particularly with Candida. The response of T cells of pemphigus patients to recall antigens of these opportunists is not clear. The aim of this study was to investigate the in vitro response of T lymphocytes from pemphigus patients to common bacterial superantigens such as streptococcal pyrogenic exotoxin A and staphylococcal enterotoxin B, and recall antigens such as Candida antigen. Changes in CD3⁺CD4⁺ and CD3⁺CD8⁺ T‐cell sub‐populations and expression of naive/memory markers (CD45RA⁺/RO⁺) on different T cells were analyzed by flow cytometry. Significant elevation in CD3⁺CD4⁺ and expression of the memory (CD45RO⁺) markers on these cells was observed both in pemphigus vulgaris and pemphigus foliaceus patients, as compared to healthy controls, upon stimulation with streptococcal pyrogenic exotoxin A and staphylococcal enterotoxin B. However, only memory T cells (CD45RO⁺) were significantly increased upon Candida antigen stimulation. Our study suggests that CD4⁺ memory T lymphocytes may modulate the pathogenic autoantibody response in pemphigus patients, and also emphasizes the possibility that the superantigen‐reactive T cells participate in the triggering of autoimmunity in pemphigus.