The role of αEβ7 integrin (CD103) and E-cadherin in epidermotropism in cutaneous T-cell lymphoma

Adhesion molecules such as integrins and cadherins are thought to play a critical role in T-cell migration and localization within the epidermis (epidermotropism). The purpose of this study was to correlate T-cell expression of the integrin GD103 and E-cadherin in cutaneous T-cell lymphoma (CTCL). Serial sections of skin biopsies from 22 patients with CTCL and 13 with benign reactive dermatitis were stained with antibodies to CD4, CD103, and E-cadherin by the avidin-biotin peroxidase technique. CD 103 was expressed on single epidermotropic CD4+ T-cells in 9/9 early stage (patch/plaque) CTCL and 6/10 reactive dermatitis biopsies. Less than 30% of dermal T-cells expressed CD103. All 4/4 late stage (tumor) CTCL were GD103–. Epidermal aggregates of CD4+T-cells (Pautrier's microabscesses) were CD103–. E-cadherin was expressed on epidermal keratinocytes and follicular and sweat gland epithelia but not on T-cells.
We conclude that CD 103 expression on cutaneous T-cells parallels the degree of epidermotropism exhibited in both neoplastic and inflammatory disorders of the skin. E-cadherin is not expressed on T-cells infiltrating the skin. Further investigation is necessary to further elucidate the interaction between CD103 and E-cadherin in facilitating trafficking of T-cells into the epidermis.     

Lack of suppressive CD4+CD25+FOXP3+ T cells in advanced stages of primary cutaneous T-cell lymphoma

Mycosis fungoides and its leukemic variant, Sezary syndrome, are the most common primary cutaneous T-cell lymphomas (CTCLs). In an ex vivo study, we investigated the percentage, phenotype, and suppressive function of CD4+CD25+ regulatory T cells (Tregs) from peripheral blood of CTCL patients. The percentage of Tregs did not differ significantly between patients and controls. Functional assays demonstrated a dichotomy in Treg function: in four out of 10 patients CD4+CD25+ T cells were incapable of suppressing autologous CD4+CD25- T-cell proliferation, whereas suppressive function was intact in the other six patients. Suppressive activity of Tregs inversely correlated with the peripheral blood tumor burden. T-plastin gene expression, used as a Sezary cell marker, confirmed that Sezary cells were heterogeneous for CD25 expression. Mixed lymphocyte reactions demonstrated that CD4+CD25- T cells from patients who lacked functional Tregs were susceptible to suppression by Tregs from healthy controls, and had not become suppressive themselves. Furthermore, we found reduced expression of Foxp3 in the CD4+CD25+ Tregs of these patients relative to the other six CTCL patients and controls. Our findings thus indicate a dysfunction of peripheral Tregs in certain CTCL patients, which correlates with tumor burden.     

Phenotypic and functional characterization of tumor infiltrating lymphocytes in mycosis fungoides: continuous growth of CD4+ CD45R+ T-cell clones with suppressor-inducer activity

Tumor-infiltrating lymphocytes (TIL) were obtained by mechanical release from a solitary rapidly grown tumor of a patient with mycosis fungoides. The preparations separated by density gradient centrifugation contained a major portion of CD3+ CD8+ WT31+ CD5- large T-cell blasts and a minor portion of non-blastic TIL predominantly of the CD3+ CD4+ phenotype. Using cDNA-probes for the constant region of the T-cell receptor beta-genes, the large cell fraction was identified as tumor by its distinct monoclonal rearrangement. TIL were expanded by culture in recombinant interleukin 2 and cloned by limiting dilution. Phenotypic analysis of expanded TIL and two clones further analyzed in more detail showed CD3+, CD4+, CD8-, and 2H4+ (CD45R+) expression. Cloned and uncloned TIL showed no NK and LAK activity, no proliferative response, and no cytotoxic activity against autologous tumor cells. These cells were unable to suppress the proliferative response of alloreactive T-cell clones stimulated by B-lymphoblastoid cell lines (i.e., they had no suppressor-effector activity), but strongly suppressed proliferation responses in allogeneic mixed lymphocyte culture (i.e., they most likely had suppressor-inducer activity). This was not the case when irradiated tumor cells were added. The present results demonstrate continuous in vitro growth of CD4+ and 2H4+ T-cell clones with suppressor-inducer activity obtained from TIL, and indicate that a subpopulation of TIL may down-regulate immune responses which may lead to suppression of antitumor immunity.     

Spectral karyotyping demonstrates genetically unstable skin-homing T lymphocytes in cutaneous T-cell lymphoma

We initially established cell lines from skin biopsies from four patients (MF8, MF18, MF19 and MF31) in early stages of cutaneous T-cell lymphoma (CTCL) in 1999. After 3 weeks of culture, skin-homing T lymphocytes were stimulated with phytohaemagglutinin. Metaphase spreads were analysed using spectral karyotyping (SKY), a molecular cytogenetic technique. MF18 and MF19 had predominantly normal karyotypes. MF8 had recurrent numerical aberrations resulting in two T lymphocyte clones: one with trisomy 21 (12/20 cells) and the other with monosomy chromosome 22 (3/20 cells). MF8 also exhibited a clonal deletion, del(5)(p15.1), as well as multiple non-clonal structural aberrations. MF31 had a clonal deletion, del(17)(p12) and other non-clonal deletions involving chromosomes 2, 5, 10, 11. MF18 had a single abnormal cell that contained two reciprocal translocations t(1;2)(q32;p21) and t(4;10)(p15.2;q24). In 2001, three of the original patients had new skin biopsies taken and cell lines were established. SKY analysis revealed the continued presence of a T-cell clone in MF8 with trisomy 21 (4/20 cells). Additionally, a new clone was seen with a del(18)(p11.2) (17/20 cells). MF31 had only one aberrant cell with a del(17)(p12). MF18 had a clonal deletion, [del(1)(p36.1) in 3/20 cells] and non-clonal aberrations involving chromosomes 3, 4, 5, 6, 12, 13, 17 and 18. Thus, three of four patients continued to show numerous numerical and structural aberrations, both clonal and non-clonal, with only MF8 having a recurring T lymphocyte clone (+21). Our findings demonstrate high genetic instability among skin-homing T lymphocytes even in early stages of CTCL. We did not see genetic instability or evidence of clones in cell lines from a patient with atopic dermatitis and one with psoriasis.     

T-cell clones from early-stage cutaneous T-cell lymphoma show no polarized Th-1 or Th-2 cytokine profile

Abstract Recent studies of the cytokine pattern in skin lesions of patients with cutaneous T-cell lymphoma (CTCL) have shown that interleukin-4 (IL-4) and Il-10, both cytokines produced by T-helper type 2 cells, dominate in these lesions. Also, in single studies, interferon-γ (IFN-γ), a major cytokine of Th-1-cells, has been found to be absent. Consequently, it has been hypothesized that immune-suppressive Th-2 cytokines may promote local growth of the malignant lymphocyte clone. However, there is so far no evidence for T-cells as the source of the Th-2 cytokines in CTCL skin lesions nor have these cytokines been investigated at a clonal T-cell level. We established a total of 120 T-cell clones (TCCs) from lesional skin and 54 TCCs from the blood of four patients with mycosis fungoides. Epidermal TCCs (mostly CD8-positive) and dermal TCCs (mostly CD4-positive) were stimulated by the mitogen concanavalin A and, seeking a polarized cytokine pattern, the supernatants were assessed by ELISA. We showed that the vast majority of TCCs were able to secrete IFN-γ and IL-4. IFN-γ-deficient TCCs occurred only in the epidermis. Some (18) TCCs were found to be either negative for IL-10 production or to produce low levels only. No significant differences were observed between blood- and skin-derived TCCs. Thus a polarized Th-2 cytokine pattern was not detectable among cultured skin-infiltrating nonmalignant T-cells (TILs) isolated from early mycosis fungoides. It therefore appears unlikely that Th-2-mediated immune suppression is a major mechanism operating in early CTCL. However, this does not exclude its role in late-stage disease. Received: 11 June 1999 / Received after revision: 13 September 1999 / Accepted: 16 September 1999     

Human T-cell leukemia virus in cutaneous T-cell lymphoma in Denmark. A possible association of HTLV and aneuploidy

Cutaneous T-cell lymphomas (CTCL) are neoplasias of mature T-cells and comprise Sezary syndrome, mycosis fungoides and some cases of lymphomatoid papulosis. Clinically this group of disorders differ from the more aggressive neoplasias of mature T-cells known as adult T-cell leukemia/lymphoma and T-cell lymphosarcoma leukemia which are associated with human T-cell leukemia virus (HTLV). We have found that of 68 patients from Denmark with CTCL ten were positive for HTLV antibodies and that the neoplastic T-cells from skin specimens in seven of eight HTLV-antibody positive patients studied by DNA flow cytometry exhibit DNA aneuploidy. Either one or two hyperdiploid cell clones were present. Aneuploidy was found in two patients with histologically verified mycosis fungoides, in four patients with histological non-diagnostic mycosis fungoides, and in one patient with lymphomatoid papulosis. The present data indicate that further seroepidemiologic survey studies of cutaneous T-cell lymphomas should include the early histological non-diagnostic stages, especially when aneuploidy is present.     

T-cell receptor β variable region (Vβ) usage in cutaneous T-cell lymphomas (CTCL) in comparison to normal and eczematous skin

Cutaneous T-cell lymphomas (CTCL) are a heterogeneous group of lymphoproliferative disorders. We investigated the variable region (Vβ) of the T-cell receptor (TCR) repertoire in CTCL and compared it to the Vβ repertoire in normal and eczematous skin. We used a panel of 21 anti-Vβ antibodies and investigated 84 biopsies of 71 CTCL patients (4 parapsoriasis en grandes plaques (PA), 1 lymphomatoid papulosis, 29 mycosis fungoides (MF), 13 Sezary syndrome (SS), 1 CD8+ CTCL, 11 pleomorphic CTCL (PLEO), 12 CTCL not classified). Six biopsies of normal skin and 6 of eczematous skin lesions served as controls. We determined the frequency of the Vβ in normal and inflamed skin and compared it to the percentage of the respective Vβ in the malignant clone of the CTCL patients. The percentage of the Vβ positive CD4+ cells in relation to the total number of T cells in normal skin and inflamed skin differed from the distribution of the Vβ families in the peripheral blood monoiiuclear cells (PBMC). Out of 71 CTCL cases, the clone was identified in 23 (32%). We identified the following clones : 1 V03.1 (1 MF), 7 V05.1 (1 CD8+ CTCL.l CTCL not classified, 1 MF, 1 PA, 3 SS), 1 V|36.7 (1 SS), 7 Vβ8.1/8.2 (2 CTCL not classified,! PLEO, 2 MF, 2 SS), 1 V012.1 (1 PLEO), 3 Vβl7.1 (2 CTCL not classified, 1 MF), 2 Vβ22.1 (1 CTCL not classified, 1 MF), 1 TCR8 (SS). The frequency of the malignant clone Vβ usage corresponded well to the repertoire of Vβ in eczematous skin but not to the repertoire in PBMC. In 6 patients, the malignant clone was mainly localized in the epidermis. In 17 cases, the clone-specific cells were distributed in epidermis and dermis equally. A retrospective analysis showed that preferential epidermal homing of the clone was associated with a non-aggressive clinical course. The Vβ usage of CTCL and eczema suggests a special cutaneous microenvironment which might be co-created by certain (bacterial?) superantigens. A preferential epidermal homing of the clone might have prognostic implications.     

Autocytotoxic T-cell clones in lichen planus

We examined the in vitro cytotoxic activity of cutaneous T-cell lines and clones from lichen planus (LP) patients against autologous epidermal keratinocytes. T cells were cultured from LP lesions and adjacent clinically normal skin and cloned by limiting dilution. Keratinocytes were cultured from LP lesions and adjacent clinically normal skin and immortalized by transfection with the E6 and E7 genes from human papillomavirus 16 (HPV16). The lesional T-cell line from one LP patient contained 27% gammadelta+ T cells and was significantly more cytotoxic against autologous lesional keratinocytes than the T-cell line from clinically normal skin. Clones isolated from the lesional T-cell line were significantly more cytotoxic against autologous lesional keratinocytes than clones isolated from the non-lesional T-cell line. Most cytotoxic clones from LP lesions were CD8+ and most non-cytotoxic clones from LP lesions were CD4+. One cytotoxic clone was CD4- and CD8- and expressed the gammadelta T-cell receptor. Two CD8+ LP lesional T-cell clones showed dose-dependent killing of HPV16 E6/E7-immortalized autologous lesional and normal keratinocytes, but no cytotoxic activity against Epstein-Barr virus-transformed autologous B-cell blasts. The cytotoxic activity of CD8+ lesional T-cell clones against autologous lesional keratinocytes was partially blocked with anti-major histocompatibility complex (MHC) class I monoclonal antibodies. These data support the hypothesis that CD8+ lesional T cells recognize an antigen associated with MHC class I on lesional keratinocytes and that CD8+ cytotoxic T cells lyse keratinocytes in LP lesions.     

Genotypic analysis of T-cell clones derived from cutaneous T-cell lymphoma lesions demonstrates selective growth of tumor-infiltrating lymphocytes

The nature of T cells contained within cutaneous lesions of cutaneous T-cell lymphoma (CTCL) has not been studied at the clonal level. T cells extracted from skin lesions of two CTCL patients were cloned by limiting dilution and propagated in interleukin-2 (IL-2) containing medium with periodic lectin stimulation. Twelve T-cell clones were derived from each patient. In both cases, genotypic analysis of the T-cell clones revealed that these clones had T-cell receptor (TCR) beta- and gamma-chain gene rearrangements distinct from the predominant, presumably malignant, clone present in the skin, lymph nodes, or blood. This suggests that they were derived from presumably reactive (non-malignant) T cells. Furthermore, these clones had gene rearrangements different from each other, indicating their multiple clonal origins. The failure to propagate in vitro the CTCL T-cell clone suggests that CTCL cells may have growth requirements different from normal T cells. Thus, conventional T-cell culturing methods using IL-2 and lectins as mitogen may selectively propagate the presumably reactive T cells contained within the skin lesions. The ability to selectively grow these reactive lesional T cells (so-called tumor infiltrating lymphocytes) raises the possibility that these cells could be used in adoptive immunotherapy.     

Cutaneous T-cell lymphoma lesional epidermal cells activate autologous CD4+ T lymphocytes: involvement of both CD1+OKM5+ and CD1+OKM5- antigen-presenting cells

Cutaneous T-cell lymphoma is characterized by infiltration of the skin by activated CD4+ T lymphocytes. The mechanism by which these T lymphocytes achieve and maintain their activated state is unknown. Antigen-specific activation of T lymphocytes is dependent upon antigen-presenting cells which express HLA-DR class II major histocompatibility complex molecules, such as epidermal Langerhans cells. In addition to CD1+DR+ Langerhans cells, cutaneous T-cell lymphoma lesional epidermis contains major histocompatibility complex class II positive non-Langerhans cell populations, including CD1+OKM5+ bone-marrow-derived cells and DR+ keratinocytes. We asked whether any of these epidermal cell populations demonstrate capacity to activate T lymphocytes. Various numbers of epidermal cells from uninvolved and involved cutaneous T-cell lymphoma plaques were therefore used to stimulate autologous CD4+ and CD8+ T lymphocytes in the absence of exogenous antigen. Involved epidermal cells potently induced proliferation of CD4+ T lymphocytes (S.I. +/- SEM = 466 +/- 45). In contrast, uninvolved epidermal cells only induced background levels of proliferation (S.I. +/- SEM = 2 +/- 0.5, N = 8, p less than 0.01). Neither involved nor uninvolved epidermal cells were able directly to activate CD8+ lymphocytes. The capability of involved epidermal cells to activate CD4+ T lymphocytes was dependent upon CD1+DR+ leukocytes and not DR+ keratinocytes, because depletion of either HLA-DR+, CD1+ or HLe1+ epidermal cells totally abrogated the T-lymphocyte proliferation. Interestingly, on a cell per cell basis CD1+DR+ cells obtained from involved skin, demonstrated relative to CD1+DR+ cells from uninvolved skin, enhanced capacity to activate CD4+ T lymphocytes. Furthermore, CD1+OKM5+ cells from involved epidermis stimulated autologous CD4+ T lymphocytes. This indicates that a unique hitherto undescribed CD1+OKM5+ epidermal antigen-presenting cell population may participate in T-lymphocyte activation. These findings provide support for the concept that the epidermal cells in cutaneous T-cell lymphoma patients, particularly the antigen-presenting cells, may contribute significantly to the activation of CD4+ malignant and/or non-malignant inflammatory T lymphocytes within the skin.     

Case report of four patients with erythrodermic cutaneous T-cell lymphoma and severe photosensitivity mimicking chronic actinic dermatitis

The marked photosensitivity associated with chronic actinic dermatitis (CAD) is presumed to be due to a T cell-mediated response to ultraviolet (UV)-induced epidermal neoantigens. Photosensitivity is, however, a rare occurrence in cutaneous T-cell lymphoma (CTCL). We discuss a series of four patients with erythrodermic CTCL who exhibited marked photosensitivity mimicking CAD. Significantly, the tumour cells had a CD8 phenotype in half of these patients. All patients had T-cell clones in skin and also demonstrated identical peripheral T-cell clones in blood or lymph node involvement. Sézary cell counts ranged from 6% to 20%, CD4/CD8 ratios from 0·22 to 23·5. Clinical presentation was striking for a marked photosensitive distribution. Monochromator irradiation testing revealed reduced minimal erythema doses throughout UVB and UVA ranges, findings consistent with those seen in CAD. All patients subsequently died from systemic disease. These findings suggest that, rarely, malignant clonal T-cell populations may recognize a unique UV-induced neoantigen, resulting in the clinical features of severe photosensitivity mimicking those seen in CAD.     

Clinical and pathological spectrum of CD8-positive cutaneous T-cell lymphomas

CD8+ T-cell lymphomas presenting in the skin are rare. We describe the clinical and histological features of 18 patients with CD8+ cutaneous T-cell tumors, which have been divided into four groups. Seven patients had precedent long histories of rashes, which progressively spread in a presentation similar to that of CD4+ mycosis fungoides (MF). Three patients had long-standing localized plaques consistent with a pagetoid reticulosis (PR) pattern. Two patients presented with erythroderma and had peripheral blood involvement consistent with a Sezary syndrome (SS) pattern and had rapidly progressive clinical courses. Six patients presented with cutaneous nodules of varying sizes and had variable outcomes, with two having rapidly progressive disease, two with indolent recurrences and a further two with complete responses to treatment. Histologically, 12 of the 18 cases showed an epidermotropic tumor infiltrate that was most marked in the three PR cases. Prominent periadnexal infiltration was seen in 11 cases. Similar to CD4+ MF, the skin-homing antigen, (cutaneous lymphocyte antigen: CLA), was strongly expressed in 13 of 16 tested cases. Expression of the cytotoxic granule protein granzyme B was noted in a majority of tumor cells in only three of 16 tested cases. We conclude that approximately half of CD8+ cutaneous T-cell lymphomas clinically and histologically resemble CD4+ MF/SS, whereas presentation as discrete nodular lesions are more common in CD8+ tumors as compared to those that express CD4.     

Hydroa vacciniforme-like primary cutaneous CD8-positive T-cell lymphoma

An 8-year-old Taiwanese girl had a 6-month history of a relapsing papulovesicular eruption on her face that resembled hydroa vacciniforme (HV). Histologically, there was a dense infiltration of large atypical lymphocytic cells expressing CD8. TCR-gamma gene rearrangement study revealed a monoclonal band present in the DNA extracted from the specimen. A diagnosis of CD8+ cutaneous T-cell lymphoma (CTCL) was made. The patient was treated with Chinese herbal drugs and her skin lesions waxed and waned. At this writing, 11 months after establishment of the diagnosis, the skin lesions have been limited to the facial area and no definite evidence of systemic involvement is noted. To our knowledge, this is the first case of CD8+ primary CTCL with clinical features resembling HV.     

Antitumour necrosis factor-alpha chimeric antibody (infliximab) inhibits activation of skin-homing CD4+ and CD8+ T lymphocytes and impairs dendritic cell function

BACKGROUND: Psoriasis is a chronic inflammatory skin disease characterized by hyperproliferation and altered differentiation of keratinocytes in reply to cytokines such as interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha, provided by infiltrating CD4+ and CD8+ T cells and natural killer cells. Infliximab is a chimeric monoclonal antibody that neutralizes both soluble and membrane-bound TNF-alpha, and that may give a long-term disease remission. OBJECTIVES: To determine the in vitro effects of infliximab on CD4+ and CD8+ T cells derived from lesional skin, and on dendritic cells (DCs). METHODS: Psoriatic T-cell lines were isolated from lesional skin of four patients with psoriasis and assayed for their proliferation, cytokine release and susceptibility to apoptotic stimuli in the presence of graded (1-100 microg mL(-1)) concentrations of infliximab. DCs were differentiated in the presence of infliximab from peripheral blood monocytes. Phenotype was assessed by fluorescence-activated cell sorting and antigen-presenting capacity in functional assays. RESULTS: In vitro activation of psoriatic as well as antigen (nickel)-specific skin-homing T cells was strongly and dose-dependently impaired by infliximab, in terms both of proliferation and of IFN-gamma release. Despite the significant reduction of IFN-gamma secretion, infliximab only marginally affected the release of interleukin (IL)-10 by skin T cells, thus determining a reduction of the IFN-gamma/IL-10 ratio at the site of inflammation. The effects were maximal when T-cell activation occurred in the absence of costimulation, or when T cells were activated by immature compared with mature DCs. In addition, skin-homing CD8+ T cells were more prominently affected by infliximab compared with CD4+ T lymphocytes, both in terms of inhibition of activation and in their susceptibility to apoptosis. Finally, infliximab directly affected the differentiation of monocyte-derived DCs, by inhibiting the expression of CD1a and CD86, and strongly impaired the antigen-presenting capacity of immature and, to a lesser extent, mature DCs. CONCLUSIONS: Infliximab directly affects psoriatic T cells and impairs the antigen-presenting capacity of DCs. These effects may help to explain the long-term disease remission obtained with the drug.     

Shortened telomere length is demonstrated in T-cell subsets together with a pronounced increased telomerase activity in CD4 positive T cells from blood of patients with mycosis fungoides and parapsoriasis

We have recently demonstrated that telomerase activity is increased and telomere length shortened in lymphocytes from peripheral blood of patients with cutaneous T-cell lymphoma. In order to determine which cell type has increased telomerase activity and shortened telomere length, CD4+, CD8+, CLA+ CD3+ and CLA- CD3+ T cells were isolated from peripheral blood of 25 patients, including 15 patients with mycosis fungoides and 10 patients with parapsoriasis. Eleven healthy individuals were used as controls; CD19+ B cells were separated from each individual as an internal control. The results showed that the increased telomerase activity was significantly predominating in the CD4+ T-cell subset. Significantly shortened telomere length was found in CD4+ and CD8+ T-cell subsets from the patients compared with the same cell subsets obtained from healthy individuals. However, no difference was observed between the subsets; CD19+ B cells collected from patients and healthy control individuals had similar telomerase activity and telomere length which was significantly different from the values found in T cells. The telomere length was significantly shorter in CLA+ CD3+ subset than in CLA- CD3+ subset. Interestingly, increased telomerase activity and shortened telomere length was also detected in CD4+ T cells from patients with parapsoriasis indicating that alteration of telomerase activity and telomere length in CD4+ T cells is an early event in the pathogenesis of cutaneous T-cell lymphoma. Thus, the results indicate that a significant high level of telomerase activity and shortened telomere length frequently occur in T cells of patients with CTCL and may reflect tumorigenesis.     

UM4D4+ (CDw60) T cells are compartmentalized into psoriatic skin and release lymphokines that induce a keratinocyte phenotype expressed in psoriatic lesions

UM4D4 (CDw60), the surface molecule of a novel antigen-independent T-cell activation pathway, was found to be highly expressed on lesional psoriatic T cells. To examine whether UM4D4 represents a T-cell activation pathway for psoriatic T cells, a T-cell line was initiated from an acute skin lesion and cloned by limiting dilution. Clonality was verified by analysis of T-cell receptor gene rearrangement. All T-cell clones tested, whether CD4+2H4+CD8-, CD4+2H4-CD8-, or CD4-CD8+CD11b-, expressed UM4D4 and were activated by the monoclonal antibody anti-UM4D4. Lesional psoriatic T-cell clones were heterogeneous in the degree of anti-UM4D4-induced proliferation and in their production of IL-2 and gamma-interferon. Lymphokines released by anti-UM4D4 activation were capable of inducing ICAM-1 and HLA-DR expression on cultured normal keratinocytes. Thus, the high expression of UM4D4 on T-cells in psoriatic skin provides an alternative mechanism for T-cell activation that may be operative in the psoriatic lesional milieu. Indeed, activation of lesional T-cells through the UM4D4 molecule resulted in release of lymphokines that directly induced keratinocytes to express a phenotype displayed in psoriatic skin lesions.     

Decreased expression of Fas (APO-1/CD95) on peripheral blood CD4+ T lymphocytes in cutaneous T-cell lymphomas

BACKGROUND: The usually protracted and indolent course of cutaneous T-cell lymphoma (CTCL) is consistent with an accumulation of lymphocytes rather than being a true proliferative disorder, perhaps as the result of defective lymphocyte apoptosis. Fas (CD95) is the main signalling membrane molecule involved in postactivation T-lymphocyte apoptosis. OBJECTIVES: To evaluate expression of Fas on circulating CD4+ lymphocytes in patients with CTCL. METHODS: Fas expression on peripheral blood CD4+ T cells in 16 patients with mycosis fungoides (patch and infiltrated plaque stages) and in four patients with Sézary syndrome was compared with that in 25 matched patients with lymphocyte-mediated cutaneous benign inflammatory disorders and in 15 subjects without inflammatory cutaneous diseases. RESULTS: Fas expression on peripheral CD4+ lymphocytes was significantly lower in patients with CTCL compared with subjects with benign inflammatory cutaneous disorders and with healthy donors. CONCLUSIONS: This pattern supports the hypothesis that a defect in T-cell apoptosis may play a part in the pathophysiology of CTCL, perhaps through abnormalities of the Fas/Fas ligand system. Alternatively, this decrease could be the result of the presence of the soluble Fas ligand molecule in the sera of patients with CTCL.     

Cutaneous histopathology of Sézary syndrome: a study of 41 cases with a proven circulating T-cell clone

Sézary syndrome is an uncommon variant of cutaneous T-cell lymphoma (CTCL) characterized by erythroderma, pruritus, adenopathy, and circulating atypical T-lymphocytes with cerebriform nuclei. The definition of Sézary syndrome can be further refined by including only patients with a circulating peripheral blood population of clonal T-cells. We have evaluated 79 skin biopsies from such a group of 41 erythrodermic patients with circulating Sézary cells and a clonal population of T-cells detected by T-cell receptor-figene rearrangement on Southern analysis of peripheral blood mononuclear cells. Histopathologic features consistent with chronic dermatitis were observed in 26/79 (33%) skin biopsy specimens, emphasizing that a non-specific histologic appearance is common. Evidence of CTCL was lacking in 11/41 patients on biopsy of their erythrodermic skin. The survival of these patients was not significantly different from 30/41 patients in whom skin biopsies revealed changes diagnostic of CTCL, such as a dermal lymphocytic band with atypical lymphocytes (18/79, 23%) or a mycosis fungoides-like infiltrate (30/79, 38%). This study confirms that non-specific cutaneous hlstopathologic findings are common in Sézary syndrome, even when a circulating T-cell clone is present. This stresses the need for peripheral blood genetic analysis and for multiple or repeat skin biopsies in erythrodermic patients when there is high clinical suspicion of CTCL.