Selective T-cell subset ablation demonstrates a role for T1 and T2 cells in ongoing acute graft-versus-host disease: a model system for the reversal of disease

Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality of allogeneic stem cell transplantation. Strategies to control GVHD while maintaining graft versus leukemia (GVL) include herpes simplex virus thymidine kinase (HSV-tk) gene transduction of donor T cells followed by treatment with ganciclovir (GCV). Alternatively, GVHD and GVL may be mediated by distinct processes. In this regard, whether cytokine polarization occurs and to what degrees various subsets of cytokine-producing T cells mediate GVHD or GVL has been an active area of research using cytokine or cytokine antibody infusion or genetically deficient mice. This study takes a different approach that allows simultaneous investigation into both the mechanisms underlying GVHD reactions and the efficacy of HSV-tk suicide gene-based T-cell deletion. A source of donor T cells, splenocytes from mice transgenic for HSV-tk controlled by elements of either the interleukin-2 (IL-2) or IL-4 promoters (IL-2-tk and IL-4-tk, respectively) was used, thus allowing investigation into the roles of T1 and T2 cells in ongoing GVHD reactions. To assess treatment rather than prevention of GVHD, GCV was started at peak disease. Remarkably, treatment at this late time point rescued mice from the clinical effects of GVHD caused by T cells expressing either transgene. Thus, both T1 and T2 cells play an important role in clinical GVHD in a minor histocompatibility antigen-mismatched setting. In addition, because clinical disease was reversible even at its maximum, these observations provide controlled evidence that this strategy of treating ongoing GVHD could be effective clinically.

Cerebral mass due to neurocutaneous melanosis: eight years later

Neurocutaneous melanosis (NCM) is associated most commonly with giant congenital melanocytic nevi (CMN), in particular those on the scalp or in a posterior axial location that are accompanied by satellite congenital nevi. It also can occur in patients with multiple medium-sized CMN. In general, the prognosis of those with symptomatic NCM is poor, even in the absence of malignancy, while the prognosis of those with asymptomatic NCM detected via screening varies and is more difficult to predict. Herein we report an asymptomatic patient with a giant CMN and multiple satellite nevi who had a screening magnetic resonance imaging (MRI) study at age 5 months that showed a rounded area of increased signal in the right temporal lobe on T1-weighted images, suggestive of parenchymal melanosis. This melanotic mass was resected at age 10 months, and histologic examination of the surgical specimen showed prominent perivascular collections of benign, pigment-containing melanocytes within cerebral tissue. The patient remains healthy 8 years later. His excellent long-term outcome and other reports of NCM with localized central nervous system (CNS) involvement apparent on MRI may have implications for management, including early imaging of patients with high-risk CMN and potential surgical intervention for NCM.

Deficiency in beta(2)-microglobulin, but not CD1, accelerates spontaneous lupus skin disease while inhibiting nephritis in MRL-Fas(lpr) nice: an example of disease regulation at the organ level

When mutations that inactivate molecules that function in the immune system have been crossed to murine lupus strains, the result has generally been a uniform up-regulation or down-regulation of autoimmune disease in the end organs. In the current work we report an interesting dissociation of target organ disease in beta(2)-microglobulin (beta(2)m)-deficient MRL-Fas(lpr) (MRL/lpr) mice: lupus skin lesions are accelerated, whereas nephritis is ameliorated. beta(2)m deficiency affects the expression of classical and nonclassical MHC molecules and thus prevents the normal development of CD8- as well as CD1-dependent NK1(+) T cells. To further define the mechanism by which beta(2)m deficiency accelerates skin disease, we studied CD1-deficient MRL/lpr mice. These mice do not have accelerated skin disease, excluding a CD1 or NK1(+) T cell-dependent mechanism of beta(2)m deficiency. The data indicate that the regulation of systemic disease is not solely governed by regulation of initial activation of autoreactive lymphocytes in secondary lymphoid tissue, as this is equally relevant to renal and skin diseases. Rather, regulation of autoimmunity can also occur at the target organ level, explaining the divergence of disease in skin and kidney in beta(2)m-deficient mice.

Perinuclear antineutrophilic cytoplasmic antibody-positive cutaneous polyarteritis nodosa associated with minocycline therapy for acne vulgaris

Minocycline is an oral antibiotic widely used for the long-term treatment of acne vulgaris. Unusual side effects of this medication include two overlapping autoimmune syndromes: drug-induced lupus and autoimmune hepatitis. In addition, in a few patients livedo reticularis or subcutaneous nodules have developed in association with arthritis and serum perinuclear antineutrophil cytoplasmic antibodies (P-ANCA) during long-term minocycline therapy. We report the cases of two young women receiving long-term minocycline therapy (>3 years) in whom P-ANCA-positive cutaneous polyarteritis nodosa developed. Both patients presented with a violaceous reticulated pattern on the lower extremities. Histologic examination of biopsy specimens from a reticulated area and a subcutaneous nodule showed necrotizing vasculitis of medium-sized arteries in the deep dermis, consistent with the diagnosis of polyarteritis nodosa. The cutaneous lesions rapidly resolved on discontinuation of minocycline and initiation of prednisone therapy. A high index of suspicion and testing for antineutrophil cytoplasmic antibody in addition to the standard antinuclear antibody panel can facilitate diagnosis of minocycline-related autoimmune disorders.

Under the microscope. Surgeons, pathologists, and melanocytic nevi

Predicting the biologic behavior of melanocytic neoplasms (benign versus malignant) based on histology is one of the most difficult challenges in surgical pathology and dermatology. Success in the field of melanocytic neoplasia can be achieved by two means: performing excisions or biopsies that maximize the obtainable histologic information and providing sufficient history.

Human TNF can induce nonspecific inflammatory and human immune-mediated microvascular injury of pig skin xenografts in immunodeficient mouse hosts

TNF activates endothelial cells to express cell surface molecules that are necessary to recruit a local infiltrate of leukocytes. Because the actions of this proinflammatory cytokine are not species restricted, we investigated whether human TNF can up-regulate porcine endothelial adhesion molecules to elicit human T cell infiltration and damage of pig skin xenografts in a chimeric immunodeficient mouse model. We have previously demonstrated the vigorous rejection of human skin allografts and the absence of injury to porcine skin xenografts in human PBMC-SCID/beige mice. Intradermal administration of human TNF at high doses (600 or 2000 ng) caused nonspecific inflammatory damage of pig skin grafts, whereas low concentrations of TNF (60 or 200 ng) resulted in human PBMC-dependent injury of porcine endothelial cells. There was a strong correlation among pig skin xenograft damage, human T cell infiltration, and the TNF-induced up-regulation of swine MHC class I and class II molecules, VCAM-1, and, in particular, the de novo expression of porcine E-selectin. The microvascular damage and leukocytic infiltration elicited by TNF were enhanced by porcine IFN-gamma, suggesting that xenografts may be less prone to cytokine-mediated injury due to the species-restricted effects of recipient IFN-gamma. Our results indicate that maintenance of a quiescent endothelium, which does not express E-selectin or other activation-dependent adhesion molecules, is important in preventing human anti-porcine T cell xenoresponses in vivo and that TNF signaling molecules and TNF-responsive gene products are appropriate therapeutic targets to protect against human T cell-mediated rejection of pig xenografts.

Primary cutaneous follicle center cell lymphoma with follicular growth pattern

Cutaneous B-cell infiltrates showing a prominent follicular growth pattern with germinal centers are thought by some authors to represent either marginal zone lymphomas with reactive germinal centers or pseudolymphomas. To establish whether a true primary cutaneous follicular lymphoma exists, we studied biopsies from 15 patients with skin lesions characterized histopathologically by the presence of B-cell infiltrates with follicular pattern. Staging investigations, including bone marrow biopsy, were negative in all patients. All were negative for bcl-2 protein expression and did not present the t(14;18). In all biopsy specimens neoplastic follicles showed 1 or more morphologic or immunophenotypic criteria of malignancy (presence of a reduced mantle zone, absence of tingible body macrophages, reduced proliferation rate). In 9 specimens a monoclonal rearrangement of J(H) genes could be detected by polymerase chain reaction analysis. After laser beam microdissection, a band of the same length could be observed in 6 probes from different follicles from the same specimen, indicating the presence of the same monoclonal population of follicle center cells. Follow-up examinations in all patients revealed no evidence of extracutaneous spread (mean follow-up, 48.7 months). Our study demonstrates that primary cutaneous follicular lymphoma represents a distinct entity of the cutaneous B-cell lymphomas. (Blood. 2000;95:3922-3928)

Humanized in vivo model for streptococcal impetigo

An in vivo model for group A streptococcal (GAS) impetigo was developed, whereby human neonatal foreskin engrafted onto SCID mice was superficially damaged and bacteria were topically applied. Severe infection, indicated by a purulent exudate, could be induced with as few as 1,000 CFU of a virulent strain. Early findings (48 h) showed a loss of stratum corneum and adherence of short chains of gram-positive cocci to the external surface of granular keratinocytes. This was followed by an increasing infiltration of polymorphonuclear leukocytes (neutrophils) of mouse origin, until a thick layer of pus covered an intact epidermis, with massive clumps of cocci accumulated at the outer rim of the pus layer. By 7 days postinoculation, the epidermis was heavily eroded; in some instances, the dermis contained pockets (ulcers) filled with cocci, similar to that observed for ecthyma. Importantly, virulent GAS underwent reproduction, resulting in a net increase in CFU of 20- to 14,000-fold. The majority of emm pattern D strains had a higher gross pathology score than emm pattern A, B, or C (A-C) strains, consistent with epidemiological findings that pattern D strains have a strong tendency to cause impetigo, whereas pattern A-C strains are more likely to cause pharyngitis.

Expression and targeting of the apoptosis inhibitor, survivin, in human melanoma

The newly described apoptosis inhibitor survivin is expressed in many human cancers and appears to play a critical part in both apoptosis regulation and cell cycle progression. Its potential role in malignant melanoma is unknown. In a panel of 30 malignant melanomas, survivin was strongly expressed in all cases (15 of 15) of metastatic malignant melanomas and 13 of 15 cases of invasive malignant melanomas by immunohistochemistry. In invasive malignant melanomas, survivin was also expressed in the in-situ component of the lesion. Survivin expression was found in all cases (11 of 11) of nevi, but not in melanocytes in sections of normal skin. The apoptosis inhibitor bcl-2 was expressed in 26 of 30 cases, but generally at lower levels than that of infiltrating lymphocytes. The mitotic index, as assessed by MIB-1 staining, was consistently higher in metastatic than invasive malignant melanomas. Assessment of apoptotic index by in situ end-labeling revealed extremely low rates of apoptosis in most malignant melanomas. Survivin expression by western blotting was detected in four human metastatic malignant melanoma cell lines but not in cultured normal human melanocytes. Transfection of both YUSAC-2 and LOX malignant melanoma cells with green fluorescence protein-conjugated survivin anti-sense or green fluorescence protein-conjugated survivin dominant negative mutant (Cys84Ala) [corrected] resulted in increased apoptosis in the absence of other genotoxic stimuli. Two-color flow cytometry confirmed that YUSAC-2 cells transfected with survivin anti-sense expressed less endogenous survivin and exhibited an increased fraction of cells with sub-G1 DNA content. These data demonstrate that apoptosis inhibition by survivin may participate in the onset and progression of malignant melanomas, and suggest that therapeutic targeting of survivin may be beneficial in patients with recurrent or metastatic disease.

Expression of the apoptosis inhibitor, survivin, in nonmelanoma skin cancer and gene targeting in a keratinocyte cell line

The recently described apoptosis inhibitor survivin is expressed in many human cancers, thus potentially contributing to disease progression and resistance to therapy. Its potential role in nonmelanoma skin cancer is unknown. By immunohistochemistry, survivin was expressed in 81% (17 of 21) of basal cell carcinomas (BCC) of both nodular and morpheaform subtypes, and in 92% (24 of 26) of cutaneous squamous cell carcinomas (SCC). Survivin was also expressed in 19 premalignant lesions of Bowen's disease (SCC in situ) and hypertrophic actinic keratosis (HAK), suggesting that its appearance occurs early during keratinocyte transformation. Survivin expression was detected by Western blotting in a model keratinocyte cell line, HaCat. Transfection of HaCat cells with green fluorescent protein (GFP)-conjugated survivin antisense or GFP-conjugated survivin dominant negative mutant (Cys84Ala) resulted in spontaneous apoptosis in the absence of other genotoxic stimuli. In GFP-conjugated survivin antisense transfectants, a decreased level of endogenous survivin was confirmed by flow cytometry. This was associated with a five-fold increase in the sub-G0/G1 fraction corresponding to apoptotic cells and a decrease in proliferating cells with 4N DNA content. These data demonstrate that apoptosis inhibition by survivin may participate in the onset and progression of both BCC and SCC, and suggest that therapeutic targeting of survivin may be beneficial in patients with recurrent or advanced disease.

Morphea limited to the superficial reticular dermis: an underrecognized histologic phenomenon

Morphea (localized scleroderma) is a disease of unknown etiology, presenting as circumscribed areas of indurated skin. Histologically, most cases of morphea feature thickened collagen bundles in the deep reticular dermis, sometimes also extending into the superficial dermis or into the subcutis. We present six cases of morphea in which typical histologic features were restricted to the superficial dermis and contrast these with 27 additional biopsies of conventional morphea seen during the same time period. Sections were stained for elastic fibers, and dermal dendritic cells were labeled with antibodies to CD34 and Factor XIIIa. All six cases showed thickened collagen bundles restricted to the superficial dermis, sparing the deep dermis and without associated evidence of lichen sclerosus et atrophicus (LSA). Dermal elastic fibers were not appreciably decreased in number. There was loss of CD34-positive dermal spindle cells in each of our six superficial examples of morphea, which was restricted to the area of altered collagen in four of the six cases. This report highlights the distinctly uncommon phenomenon of morphea presenting solely as alteration of the superficial reticular dermis, without features of LSA. The selective loss of CD34-labeled spindle cells may provide information regarding the role of these putative immune accessory cells in morphea. Recognition of this manifestation of morphea may be helpful diagnostically.

Expression and localization of thymidine phosphorylase/platelet-derived endothelial cell growth factor in skin and cutaneous tumors

Thymidine phosphorylase/platelet-derived endothelial cell growth factor (TPase/PD-ECGF) is a catabolic enzyme that has been shown to be chemotactic for endothelial cells in vitro and angiogenic in vivo. TPase/PD-ECGF expression is increased in a variety of tumors. In the skin, TPase is active in normal keratinocytes in vitro and in vivo. Our objective was to study the expression and localization of TPase/PD-ECGF by immunohistochemical analysis in normal skin and cutaneous tumors and to correlate this information with enzymatic activity of TPase. TPase/PD-ECGF expression was observed in keratinocytes with intense staining of the infundibulum of hair follicles but no staining of hair bulbs. Expression localized primarily to the nucleus of keratinocytes in the basal layer but was more intense and cytoplasrmic in suprabasal keratinocytes. Increased expression of TPase/PD-ECGF in differentiated cells was confirmed by in vitro studies of TPase activity. In cutaneous tumors, there was positive staining for TPase/ PD-ECGF in squamous cell carcinomas (10/10), eccrine poromas (3/4), eccrine syringomas (4/4), trichoepitheliomas (1/3), and tumors of the follicular infundibulum (2/3) and melanomas (5/8). There was no staining of any intradermal nevi (0/2), basal cell carcinomas (0/10) or Merkel cell carcinoma (0/1). We conclude TPase/PD-ECGF is found throughout the epidermis and its expression increases with differentiation of keratinocytes. In cutaneous tumors, expression of TPase/PD-ECGF may be linked to the cell of origin of the tumor as well as the tumor's degree of differentiation.

Cutaneous T-cell lymphoma. Refinement in the application of controversial histologic criteria

The term cutaneous T-cell lymphoma was originally coined to encompass the spectrum of mycosis fungoides and Sézary syndrome. It has become increasingly evident that the histopathologic diagnosis of CTCL can be exceedingly challenging. A series of recent studies, however, have helped clarify the nature of the histologic findings in CTCL. Recently reported histologic data on mycosis fungoides, Sézary syndrome, and their variants is emphasized in this article, with special focus given to the findings in early lesions. A brief summary of lymphocyte immunophenotyping and the role of T-cell reception gene rearrangements in CTCL is included.

Familial multiple basaloid follicular hamartomas: A report of two affected sisters

Basaloid follicular hamartoma (BFH) is one of several benign skin tumors that may occur in multiple and solitary forms. While the histologic findings of BFH may be observed in a variety of clinical settings, familial multiple BFH represents a distinct clinical entity characterized by tiny flesh-colored papules scattered predominantly over the face. We present two sisters with this rare condition and review the clinical and histologic differential diagnosis of familial multiple BFH.

Integrins alpha4beta7 and alphaEbeta7 are expressed on epidermotropic T cells in cutaneous T cell lymphoma and spongiotic dermatitis

Integrin alpha4beta7 has been associated with tissue-specific homing of malignant and inflammatory lymphocytes to gastrointestinal mucosa, whereas integrin alphaEbeta7 has been associated with intraepithelial lymphocytes in both the gut and the skin. This prompted us to examine the expression of alpha4beta7 on skin-infiltrating lymphocytes in 12 cases of patch/plaque stage cutaneous T cell lymphoma (CTCL) and in 4 cases of spongiotic dermatitis, which also display intraepidermal T cell accumulation. alpha4beta7 was found to be expressed on 64.8+/-7.4% of intraepidermal and 39.1+/-5.0% of intradermal T lymphocytes in CTCL. There was a significant positive correlation (r=0.58) between the degree of epidermotropism and the percentage of intraepidermal T cells expressing alpha4beta7. Similar findings were observed in spongiotic dermatitis, indicating that this result is not unique to malignant T cells. We evaluated staining of T cells in the same specimens for presence of alphaEbeta7 and observed a strong correlation between the expression of both beta7 integrins in each specimen. Staining with antibodies directed against the known ligands of alpha4beta7 was also performed on skin biopsies from CTCL patients. There was significantly increased dermal microvascular endothelial expression of vascular cell adhesion molecule-1 in lesional compared with nonlesional skin, and in nonlesional skin compared with skin of normal control subjects. Dermal and epidermal expression of the CS-1 domain of fibronectin was present but not increased in lesional biopsies compared with nonlesional or normal controls, whereas expression of mucosal addressin cell adhesion molecule-1 was not detectable in any skin biopsy specimens. In summary, alpha4beta7, like alphaEbeta7, is expressed at high levels on epidermotropic T cells and may interact with endothelial cell vascular cell adhesion molecule-1 as part of stepwise recruitment of lymphocytes from the blood to the epidermis.

A common human skin tumour is caused by activating mutations in beta-catenin

WNT signalling orchestrates a number of developmental programs. In response to this stimulus, cytoplasmic beta-catenin (encoded by CTNNB1) is stabilized, enabling downstream transcriptional activation by members of the LEF/TCF family. One of the target genes for beta-catenin/TCF encodes c-MYC, explaining why constitutive activation of the WNT pathway can lead to cancer, particularly in the colon. Most colon cancers arise from mutations in the gene encoding adenomatous polyposis coli (APC), a protein required for ubiquitin-mediated degradation of beta-catenin, but a small percentage of colon and some other cancers harbour beta-catenin-stabilizing mutations. Recently, we discovered that transgenic mice expressing an activated beta-catenin are predisposed to developing skin tumours resembling pilomatricomas. Given that the skin of these adult mice also exhibits signs of de novo hair-follicle morphogenesis, we wondered whether human pilomatricomas might originate from hair matrix cells and whether they might possess beta-catenin-stabilizing mutations. Here, we explore the cell origin and aetiology of this common human skin tumour. We found nuclear LEF-1 in the dividing tumour cells, providing biochemical evidence that pilomatricomas are derived from hair matrix cells. At least 75% of these tumours possess mutations affecting the amino-terminal segment, normally involved in phosphorylation-dependent, ubiquitin-mediated degradation of the protein. This percentage of CTNNB1 mutations is greater than in all other human tumours examined thus far, and directly implicates beta-catenin/LEF misregulation as the major cause of hair matrix cell tumorigenesis in humans.

Immunohistochemical comparison of cutaneous lymphadenoma, trichoblastoma, and basal cell carcinoma: support for classification of lymphadenoma as a variant of trichoblastoma

Cutaneous lymphadenoma is an uncommon basaloid epithelial tumor of uncertain histogenesis, most recently classified as a variant of trichoblastoma. Because characteristic immunohistochemical findings have been reported in trichoblastomas, we evaluated the staining patterns of five cutaneous lymphadenomas and compared the results to those of ten trichoblastomas and ten nodular basal cell carcinomas (BCCs), using antibodies to cytokeratin 20 (CK20), bcl-2, and CD34. In addition, because lymphadenomas contain intraepithelial S100-positive putative Langerhans cells, we compared staining of all tumor groups for S100 protein and CD1a. We also attempted to corroborate recent reports of CD30-positive activated lymphocytes in lymphadenomas. We identified CK20-positive Merkel cells in 3/5 lymphadenomas, 7/10 trichoblastomas, and none of the BCCs. Staining for bcl-2 accentuated the peripheral epithelial layer in all lymphadenomas and in 3/10 trichoblastomas, while the remaining trichoblastomas and all BCCs stained diffusely. There was stromal staining with CD34 in two lymphadenoma, 4 trichoblastomas, and 3 BCCs. All lymphadenomas featured numerous intraepithelial S100-positive cells which were also positive for CD1a in three cases tested. In addition, 8/10 trichoblastomas and 2/10 BCCs contained modest numbers of cells labelling for S100 and CD1a. Two of three lymphadenomas contained rare single cells resembling histiocytes faintly positive for CD30, and similar cells labelled for CD68. We conclude that the similar staining patterns of lymphadenomas and trichoblastomas support the classification of lymphadenoma as a variant of trichoblastoma. Staining with CD34 does not reliably distinguish between these tumors and BCCs. Lymphadenomas, trichoblastomas, and BCCs may all contain Langerhans' cells. The relationship between these cells and the striking lymphoid infiltrates seen in lymphadenomas is not clear. In our cases, the CD30-positive cells in lymphadenomas appear to represent histiocytes rather than activated lymphocytes.

Epithelioid cell histiocytoma: a simulant of vascular and melanocytic neoplasms

Epithelioid cell histiocytoma (ECH) is an unusual and still poorly recognized variant of benign fibrous histiocytoma. Epithelioid cell histiocytoma differs from most benign fibrous histiocytomas in five important ways: the predominance of epithelioid cells, relative lack of secondary elements (such as giant cells, foamy, or hemosiderin-laden macrophages), relative sharp circumscription, prominent vascularity, and centering in the papillary dermis in most cases. A strong resemblance to melanocytic and vascular lesions has been noted, and a recent case was reported with features suggesting endothelial origin. Fifteen new cases of ECH, including one example of the rare deep cellular variant, are presented herein, with emphasis on features mimicking vascular and melanocytic neoplasms. Labeling with endothelial markers, including previously unreported CD-31 labeling, showed abundant vascular staining, which may be challenging to interpret, but which does not indicate an endothelial origin of ECH.

Extracorporeal photochemotherapy in human and murine graft-versus-host disease

Extracorporeal photochemotherapy (ECP) is an immunotherapy that has found a role in the therapy of cutaneous T cell lymphoma, a disease of mature activated T cells. Graft-versus-host disease (GVHD) is also mediated by activated T cells, and thus often responds to therapies that target T cells. Murine models for both GVHD and ECP can be combined to study the impact of this immunotherapy on GVHD. In this paper we present a patient with GVHD who demonstrated a beneficial therapeutic response to treatment with ECP. The findings of this case are compared with the observations from a murine model for GVHD-ECP. The potential mechanisms of ECP in the treatment of GVHD are discussed. along with the similarities observed with ECP in the treatment of other conditions.

Dermal microvascular injury in the human peripheral blood lymphocyte reconstituted-severe combined immunodeficient (HuPBL-SCID) mouse/skin allograft model is T cell mediated and inhibited by a combination of cyclosporine and rapamycin

We have analyzed the mechanism of human endothelial injury in a human peripheral blood lymphocyte-severe combined immunodeficient (huPBL-SCID) mouse/human skin graft model of allograft injury and examined the effect of immunosuppressive drugs on this process. In this model, split-thickness human skin containing the superficial dermal microvessels was grafted onto immunodeficient C.B-17 SCID or SCID/beige mice and allowed to heal. Human peripheral blood mononuclear cells (PBMCs) allogeneic to the skin, when subsequently introduced by intraperitoneal injection, caused destruction of the human dermal microvasculature by day 16, evident as endothelial cell sloughing and thrombosis. In the same specimens, mouse microvessels that invaded the human skin graft were uninjured. Human microvascular cell injury was accompanied by a mononuclear cell infiltrate consisting of approximately equal numbers of human CD4+ and CD8+ T cells, some of which contained perforin-positive granules. We found no evidence of human natural killer cells and noted occasional human, but not mouse, macrophages at a frequency indistinguishable from that resident in skin on animals not receiving human PBMCs. These human T cell infiltrates did not extend into adjacent mouse skin. Human immunoglobulin G antibody was detected in the blood and was diffusely present throughout mouse and human tissues in SCID mice receiving PBMCs. Mouse C3 was detected on human dermal vessels in both unreconstituted control animals and those that received PBMCs. Blood and tissues from mice injected with PBMCs depleted of B cells showed no human immunoglobulin, but circulating CD3+ cells were detected by flow cytometry at levels comparable with those of animals receiving whole PBMCs. Significantly, skin graft infiltration by human T cells and human dermal microvascular injury were equivalent in the B cell-depleted and whole-PBMC-reconstituted mice. Mice inoculated with PBMCs depleted of CD8+ T cells developed microvascular injury and infiltrates containing perforin-expressing CD4+ T cells. These data suggested a cytolytic T cell-dependent mechanism of microvessel injury. We then tested the ability of T cell immunosuppressants, cyclosporine and rapamycin, to attenuate vessel damage. Neither cyclosporine nor rapamycin alone effectively reduced either mononuclear cell infiltration or vascular injury. However, a combination of the two agents reduced both parameters. We conclude that the huPBL-SCID/skin allograft model may be used both to study cytolytic T cell-mediated rejection and to test the effect of immunosuppressive drug strategies in vivo in a small-animal model of human immune responses.

Mycosis fungoides palmaris et plantaris or acral pagetoid reticulosis?

There has been ongoing debate about the nature of Woringer-Kolopp disease (unilesional pagetoid reticulosis). Despite the histologic resemblance to mycosis fungoides, these lesions are typically solitary and indolent. Recently, cutaneous plaques of epidermotropic lymphocytes restricted to acral sites resembling Woringer-Kolopp disease were reported to show T-cell clonality, leading to the designation mycosis fungoides palmaris et plantaris. We describe a similar case of recurrent plaques on palms and soles of a 45-year-old man that persisted for >14 years without other cutaneous or systemic disease. Histologically, the lesions were comprised of epidermotropic atypical lymphocytes with sparse dermal infiltrates. Immunohistochemically, the majority of intraepidermal lymphocytes labeled as CD8-positive suppressor/cytotoxic T cells and expressed alphaE beta7 (CD103), an integrin associated with epitheliotropism. Polymerase chain reaction studies revealed similar clonal gene rearrangements of T-cell receptors beta and gamma in tissue from both palm and sole. In view of these findings, the diagnosis of mycosis fungoides palmaris et plantaris may be appropriate. To date, however, the lesions have remained localized and continue to resolve spontaneously. As such, the behavior is similar to what has been described as pagetoid reticulosis. Long-term follow-up will be necessary to determine the biologic potential of this disease.

Melanoma x macrophage hybrids with enhanced metastatic potential

Studies were conducted on the hypothesis that melanoma metastasis might be initiated through the generation of hybrids comprised of cells of the primary tumor and tumor-infiltrating leukocytes. Fusion hybrids were generated in vitro between weakly metastatic Cloudman S91 mouse melanoma cells and normal mouse or human macrophages. Hybrids were implanted s.c. in the tail and mice were monitored for metastases. Controls included parental S91 cells, autologous S91 x S91 hybrids, and B16F10 melanoma cells. Of 35 hybrids tested, most were more aggressive than the parental melanoma cells, producing metastases sooner and in more mice. A striking characteristic was heterogeneity amongst hybrids, with some lines producing no metastases and others producing metastases in up to 80% of mice. With few exceptions, hybrids with the highest metastatic potential also had the highest basal melanin content whereas those with the lowest metastatic potential were basally amelanotic, as were the parental melanoma cells. A spontaneous in vivo supermelanotic hybrid between an S91 tumor cell and DBA/2J host cell was one of the most metastatic lines. Hybrids with the highest metastatic potential also exhibited markedly higher chemotaxis to fibroblast-conditioned media. Histologically, the metastatic hybrids demonstrated vascular invasion and spread to distant organs similar to that of metastatic melanomas in mice and humans. Thus previous findings of enhanced metastasis in leukocyte x lymphoma hybrids can now be extended to include leukocyte x melanoma hybrids. Whether such hybridization is a natural cause of metastasis in vivo remains to be determined; however the fusion hybrids with genetically-matched parents described herein so closely resembled naturally-occurring metastatic melanoma cells that they could serve as useful new models for studies of this complex and deadly phenomenon.

Psoralen photochemotherapy, clinical efficacy, and photomutagenicity: the role of molecular epidemiology in minimizing risks

Photochemotherapy employing 8-methoxypsoralen and ultraviolet radiation (PUVA) is widely used in the treatment of psoriasis. The photoactivation of psoralens in skin cells leads to DNA photoadduct formation which may be responsible for the efficacy of PUVA. Subsequent mutations may lead to the increased incidence of squamous cell carcinoma (SCC). Mutations in the p53 tumor suppressor gene have been detected in many human cancers. In this review, p53 mutation spectra in murine and human SCC are compared to those obtained from murine cells and skin treated with PUVA as well as to the p53 mutation spectrum in human solar SCC. While the expected psoralen-type mutations at alternating AT sites were detected in the treated cells and murine SCC (average frequency > 40%), such mutations were not commonly detected in the human SCC (< 10%). Other common mutations in the human SCC included: CG-->TA transitions (18%) and CG-->AT and TA-->GC transversions (17 and 25%, respectively). In addition, the frequency of UVB-type mutations at dipyrimidine sites (CC-->TT) in the SCC PUVA-treated psoriasis patients was comparable to that in patients with SCC from only solar exposure. A review of therapeutic history of these patients showed that many had also received UVB phototherapy. Furthermore, because sunlight is thought to be beneficial for psoriasis, nontherapeutic, casual UVB exposure cannot be excluded. Thus, the PUVA SCC may have arisen from the solar mutations and PUVA may enhance tumor progression by other epigenetic effects.

Pathogenesis of autoimmunity in alphabeta T cell-deficient lupus-prone mice

Murine lupus in MRL mice has been strongly attributed to alphabeta T cell-dependent mechanisms. Non-alphabeta T cell-dependent mechanisms, such as gammadelta T cells, have been shown to drive antibody and autoantibody production, but they have not been considered capable of inducing end-organ disease. Here, we have expanded upon the findings of such previous work by examining the mechanism and extent of end-organ disease attainable via gammadelta T cells and/or non-alphabeta T cell-dependent mechanisms, assessing two prototypical lupus lesions, renal and skin disease, in TCR alpha -/- MRL mice that possessed either functional or defective Fas antigen (Fas + or lpr). Observed to 1 year of age, TCR alpha -/- MRL mice developed disease characterized by increased mortality, overt renal disease and skin lesions. While delayed in onset and/or reduced in severity compared with TCR alpha +/+ MRL/lpr animals, renal and skin lesions in alphabeta T cell-deficient animals were clearly increased in severity compared with age-matched control non-autoimmune mice. In contrast to TCR alpha +/+ MRL mice, whose disease reflected pan-isotype immune complex deposition with significant complement fixation, renal disease in TCR alpha -/- MRL animals reflected predominantly IgG1 immune complex deposition, with poor complement fixation. Thus, this study demonstrates conclusively that non-alphabeta T cell-dependent mechanisms can induce renal and skin injury in murine lupus, but at least in the kidney, only via humoral autoimmunity of a relatively non-pathological isotype which results in the delayed onset of end-organ damage.

Discoid lupus erythematosus presenting as asymmetric posterior blepharitis

PURPOSE

To describe the ophthalmic findings of patients with discoid lupus erythematosus.

METHOD

We describe two women who originally were thought to have asymmetric posterior blepharitis; however, the involved eyelid also had an erythematous, scaly cutaneous lesion.

RESULT

In both patients, histology and immunofluorescence studies performed on cutaneous biopsy specimens established the diagnosis of discoid lupus erythematosus.

CONCLUSIONS

It is important to diagnose discoid lupus of the eyelids because misdiagnosis can delay treatment and thus lead to deformities of the eyelid margin. Misdiagnosis can also lead to a complicated full-thickness eyelid biopsy and delay the diagnosis of systemic lupus erythematosus.

Pig but not human interferon-gamma initiates human cell-mediated rejection of pig tissue in vivo

Split-thickness pig skin was transplanted on severe combined immunodeficient mice so that pig dermal microvessels spontaneously inosculated with mouse microvessels and functioned to perfuse the grafts. Pig endothelial cells in the healed grafts constitutively expressed class I and class II major histocompatibility complex molecules. Major histocompatibility complex molecule expression could be further increased by intradermal injection of pig interferon-gamma (IFN-gamma) but not human IFN-gamma or tumor necrosis factor. Grafts injected with pig IFN-gamma also developed a sparse infiltrate of mouse neutrophils and eosinophils without evidence of injury. Introduction of human peripheral blood mononuclear cells into the animals by intraperitoneal inoculation resulted in sparse perivascular mononuclear cell infiltrates in the grafts confined to the pig dermis. Injection of pig skin grafts on mice that received human peripheral blood mononuclear cells with pig IFN-gamma (but not human IFN-gamma or heat-inactivated pig IFN-gamma) induced human CD4(+) and CD8(+) T cells and macrophages to more extensively infiltrate the pig skin grafts and injure pig dermal microvessels. These findings suggest that human T cell-mediated rejection of xenotransplanted pig organs may be prevented if cellular sources of pig interferon (e.g., passenger lymphocytes) are eliminated from the graft.

Blockade of CD2-LFA-3 interactions protects human skin allografts in immunodeficient mouse/human chimeras

A human skin allograft injury model in immunodeficient mice, engrafted with human peripheral blood mononuclear cells from a different donor, has been used to test whether reagents that block human T cell CD2 interactions with its principal ligand, LFA-3 (CD58), can inhibit immune reactions in vivo. In this model, human skin grafts show a reproducible pattern of progressive human T-cell infiltration and human graft microvascular injury that resembles human first-set skin graft rejection. Murine Mab to human LFA-3 or human LFA-3-IgG1 fusion protein, but not isotype-matched control antibodies, each markedly protected skin grafts from leukocyte infiltration and injury. These data provide the first evidence that LFA-3 functions in vivo and establish the ability of this new model to test human-specific immune modulators.

An unexpected spectrum of p53 mutations from squamous cell carcinomas in psoriasis patients treated with PUVA

Photochemotherapy employing 8-methoxypsoralen and long-wavelength ultraviolet radiation (UVA, 320-400 nm) is widely used in the treatment of psoriasis. The photoactivation of psoralens in skin cells leads to formation of DNA photoadducts which may be responsible, at least in part, for the efficacy of these photochemotherapies. However, mutations arising from these adducts may also lead to the well-characterized increased incidence of squamous cell carcinoma. Mutations in the p53 tumor suppressor gene have been detected in many human cancers. To determine whether p53 mutations occur in squamous cell carcinomas in PUVA patients, PCR was used to amplify the exons (5-9) in which other studies have found a high frequency of point mutations. Gel electrophoresis was used to detect single-strand conformational polymorphisms. Aberrantly migrating bands were excised, reamplified and sequenced. Thirty-four specimens from 10 patients were examined. Specimens from one patient who had received no phototherapy as well as from normal controls were also analyzed. Five of the 10 patients showed at least one p53 mutation. In contrast to previously reported psoralen-induced p53 mutations in mice, the expected psoralen type mutations at alternating AT sites were not detected. All but two of the altered sequences occurred at dipyrimidine sites which is typical of solar type mutations. Two C-->T mutations and two dipyrimidine mutations (CC-->TT) were found. Other mutations included: C-->G, G-->T, C-->A and an 18 bp deletion. A review of therapeutic history of these patients showed that some had also received UVB phototherapy. Furthermore, because sunlight is thought to be beneficial for psoriasis, nontherapeutic, casual UVB exposure cannot be excluded. Our observations suggest that the SCC may have arisen from the solar mutations and that PUVA may enhance tumor progression or immune suppression.

alpha beta T cell regulation and CD40 ligand dependence in murine systemic autoimmunity

To explore the mechanisms by which alpha beta T cells and gamma delta T cells regulate systemic autoimmunity, lupus-prone mice were rendered deficient in CD40 ligand and/or alpha beta T cells by intercrossing CD40L -/- and TCR-alpha -/- knockouts, generating CD40L-intact or -deficient (CD40L+ or CD40L-), alpha beta T cell-intact or -deficient (alpha beta+ or alpha beta-) MRL-lpr/lpr animals. As expected, CD40L+ alpha beta+ mice developed high titer autoantibodies along with severe renal and cutaneous disease. CD40L+ alpha beta- animals developed lower levels of autoantibodies, accompanied by less severe or delayed renal and cutaneous disease. CD40L- alpha beta+ mice developed even lower titers of autoantibodies and less severe renal disease yet developed cutaneous lesions indistinguishable from those of CD40L+ alpha beta+ disease. Most surprisingly, CD40L- alpha beta- animals developed higher levels of some autoantibodies than did CD40L- alpha beta+ mice and developed renal disease similar in severity to CD40L+ alpha beta- counterparts; however, they failed to develop skin disease. Thus, disruption of CD40L and alpha beta T cells provides a novel dissection of the physiology and pathology of murine lupus; while these data confirm previous findings demonstrating a role for CD40L-dependent, alpha beta T cell-dependent mechanisms in autoantibody production and renal disease in murine lupus, they also: 1) establish that alpha beta T cells may drive autoimmune skin disease by a CD40L-independent mechanism; 2) identify a role for CD40L in non-alpha beta T cell-dependent autoantibody production and autoimmune skin disease; and 3) suggest a role for alpha beta T cells in the down-regulation of autoimmunity driven by other T cells. Thus, both alpha beta and non-alpha beta T cells, such as gamma delta T cells, regulate systemic autoimmunity by CD40L-dependent and -independent mechanisms.

alpha beta T cell regulation and CD40 ligand dependence in murine systemic autoimmunity

To explore the mechanisms by which alpha beta T cells and gamma delta T cells regulate systemic autoimmunity, lupus-prone mice were rendered deficient in CD40 ligand and/or alpha beta T cells by intercrossing CD40L -/- and TCR-alpha -/- knockouts, generating CD40L-intact or -deficient (CD40L+ or CD40L-), alpha beta T cell-intact or -deficient (alpha beta+ or alpha beta-) MRL-lpr/lpr animals. As expected, CD40L+ alpha beta+ mice developed high titer autoantibodies along with severe renal and cutaneous disease. CD40L+ alpha beta- animals developed lower levels of autoantibodies, accompanied by less severe or delayed renal and cutaneous disease. CD40L- alpha beta+ mice developed even lower titers of autoantibodies and less severe renal disease yet developed cutaneous lesions indistinguishable from those of CD40L+ alpha beta+ disease. Most surprisingly, CD40L- alpha beta- animals developed higher levels of some autoantibodies than did CD40L- alpha beta+ mice and developed renal disease similar in severity to CD40L+ alpha beta- counterparts; however, they failed to develop skin disease. Thus, disruption of CD40L and alpha beta T cells provides a novel dissection of the physiology and pathology of murine lupus; while these data confirm previous findings demonstrating a role for CD40L-dependent, alpha beta T cell-dependent mechanisms in autoantibody production and renal disease in murine lupus, they also: 1) establish that alpha beta T cells may drive autoimmune skin disease by a CD40L-independent mechanism; 2) identify a role for CD40L in non-alpha beta T cell-dependent autoantibody production and autoimmune skin disease; and 3) suggest a role for alpha beta T cells in the down-regulation of autoimmunity driven by other T cells. Thus, both alpha beta and non-alpha beta T cells, such as gamma delta T cells, regulate systemic autoimmunity by CD40L-dependent and -independent mechanisms.

Lymphomatoid granulomatosis of the skin and lung. An angiocentric T-cell-rich B-cell lymphoproliferative disorder

OBJECTIVE

To test the recent hypothesis that lymphomatoid granulomatosis (LYG) is a clonal B-cell proliferative process related to Epstein-Barr virus (EBV).

BACKGROUND AND DESIGN

Historically, LYG has been classified as an angiocentric T-cell lymphoproliferative disorder. To further characterize LYG in the skin, we analyzed for EBV RNA in lymphocytes using in situ hybridization, coupled with colabeling for B-cell and T-cell markers. Clonality of lymphocytes was assessed by polymerase chain reaction using primers for immunoglobulin heavy chain genes and T-cell receptor beta and gamma genes.

SETTING

Academic referral center.

PATIENTS

In a 5-year retrospective review, we identified 4 patients with classic clinical and pathologic features of LYG in skin and lung, and tissue available from both sites.

MAIN OUTCOME MEASURES

The presence or absence of EBV RNA and clonal gene rearrangements in cutaneous and pulmonary lesions of LYG.

RESULTS

Biopsy specimens of skin and lung in all patients revealed angiocentric infiltrates predominantly composed of T lymphocytes. Epstein-Barr virus RNA was identified in the skin of 1 patient and the lung of 3 patients, and was restricted to B cells. Polymerase chain reaction revealed clonal immunoglobulin heavy chain gene rearrangements and no clonal rearrangement of T-cell receptor genes in skin and lung tissue of all patients.

CONCLUSIONS

At least some examples of LYG in the skin and lung are characterized by a clonal proliferation of B lymphocytes, some of which contain EBV RNA. The B cells are typically scarce and may be obscured by striking angiocentric T-cell infiltrates.

Permeability characteristics of cultured endothelial cell monolayers

The purpose of this study was to characterize the permeability characteristics of an in vitro endothelial cell monolayer system and relate this information to available in vivo data. We cultured bovine fetal aortic endothelial cells on fibronectin-coated polycarbonate filters and confirmed that our system was similar to others in the literature with regard to morphological appearance, transendothelial electrical resistance, and the permeability coefficient for albumin. We then compared our system with in vivo endothelium by studying the movement of neutral and negatively charged radiolabeled dextran tracers across the monolayer and by using electron microscopy to follow the pathways taken by native ferritin. There were a number of differences. The permeability of our monolayer was 10-100 times greater than seen in intact endothelium, there was no evidence of "restricted" diffusion or charge selectivity, and ferritin was able to move freely into the subendothelial space. The reason for these differences appeared to be small (0.5-2.0 micron) gaps between 5 and 10% of the endothelial cells. Although the current use of cultured endothelial cells on porous supports may provide useful information about the interaction of macromolecules with the endothelium, there appear to be differences in the transendothelial permeability characteristics of these models and in vivo blood vessels.

Early cell alterations induced by histamine and epinephrine in rabbit lung

This study was concerned with the early effects on lung cells of infusion of 18 micrograms/kg histamine to the rabbit. For comparison purposes, other rabbits received a bolus of 0.4 micrograms/kg epinephrine. After administration, the lungs were immediately fixed by vascular perfusion of osmium tetroxide. In the group that received histamine, we observed selective alterations in the type I epithelial cells of the alveolar wall, consisting of localized thickening, increased number of cytoplasmic ribosomes, and homogeneity and increased electron density with reduction of the number of plasmalemmal vesicles. These alterations were quantitated; the vesicular load (no. of vesicles/cm2) was computed separately for each cell front of epithelial and endothelial cells. Epinephrine induced only edema in epithelial and endothelial cells, resulting in high electron lucency, thickening, and irregular cell profiles. We interpret the alterations seen in histamine-treated animals as reflecting uptake of histamine by the alveolar epithelium leading to an increased level of metabolic activity. Histamine induced no interstitial edema and no immediate reduction of capillary volume. The cellular edema related to epinephrine, a substance which is not taken up or metabolized by the lung, represented a form of cell injury.

Alveolar epithelial lesions induced by angiotensin in rabbit lungs

We slowly administered a bolus of 10 micrograms/kg of angiotensin II in saline to anesthetized rabbits. Their lungs are fixed by vascular perfusion of fixatives 2-3 minutes after the end of the infusion. Electron-microscopic examination of the lung parenchyma did not reveal signs of hemodynamic edema, but several epithelial alterations were observed that could be interpreted as the result of incorporation of plasmalemmal vesicles into the plasma membrane: these included undulating membrane profiles, transcellular channels formed by coalescing vesicles, and/or deep infoldings of the cell membrane. These appear to have the capability of causing demarcations in the cellular cytoplasm of Type I epithelial cells, which result in cell fractionation and localized destruction of the squamous alveolar epithelium, which leads to denudation of the basement membrane from the air side. These epithelial lesions were often associated with intracapillary platelet-fibrin aggregates, and cell destruction was most apparent in the presence of substantial amounts of fibrin. Morphologic signs of damage of the capillary endothelial cells existed but were less pronounced; in particular, there was no endothelial denudation under the platelet aggregates.

Secretion of Weibel-Palade bodies observed in extra-alveolar vessels of rabbit lung

We fixed rabbit lungs by perfusion of osmium into the pulmonary artery and examined in light and transmission electron microscopy a large number of extra-alveolar vessels with a diameter of 0.1-0.25 mm, with emphasis on Weibel-Palade bodies (endothelial specific granules). Weibel-Palade bodies are organelles specific to endothelial cells. Their function is unknown, but they are useful markers for identification of endothelial cells in culture. We were able to observe release of the content of these bodies into the vascular lumen; this indicates that they are secretory.

Early tissue damage in ethchlorvynol-induced alveolar edema in rabbit lung

The purpose of this study was to examine the morphologic changes that occur in the early stages of intraalveolar edema. Anesthetized rabbits were intravenously administered a bolus of 40 mg/kg of ethchlorvynol, a mild hypnotic known to induce respiratory distress syndrome in humans and laboratory animals when given intravenously. After 15 min their lungs were fixed for transmission electron microscopy. Examination revealed variable amounts of irregularly distributed intraalveolar edema with erythrocytes and fibrin strands that coexisted with modest or nonexisting interstitial edema suggesting that primary hemorrhagic alveolar flooding had taken place. Most alveolar epithelial and endothelial cells appeared normal except in localized areas. In lungs fixed by vascular perfusion, in which normal capillaries were flushed, obstructions were noticed in alveolar corner capillaries. These areas were identified by light microscopy and selectively sectioned for electron microscopy. They contained intravascular cell-fibrin aggregates consisting of plugs of degranulated platelets, fibrin, erythrocytes, and leukocytes. Endothelial and epithelial cells in the vicinity of the plugs showed variable degrees of injury. In places the damage was so severe that vascular and alveolar spaces were separated only by the basal lamina. Our work shows the previously unnoticed existence of capillary microemboli or microthrombi in a well-known experimental model of respiratory distress syndrome and suggests extravasation of blood elements through discrete sites of cell injury associated with the fibrin-platelet aggregates rather than diffuse increase of permeability as cause of early alveolar flooding.

Distribution of vesicles in cells of air-blood barrier in the rabbit

Vesicular transport has been proposed as a pressure-independent shuttle mechanism for transport of macromolecules across thin cells. The vesicular populations of cells found in the gas-exchanging parenchyma were quantitated by morphometric means. We found that the numerical densities (number of vesicles/unit of volume) were comparable in endothelial (131/micrometer 3) and epithelial (145/microm3) type I cells but much smaller for interstitial cells. The vesicular loads or numbers of vesicles/unit of surface area were computed separately for each cell front (luminal and abluminal) and found to be similar for all surfaces, ranging from 150 to 196/micrometer 2 except for the interstitial front of epithelial cells where the load was higher (230/micrometer 2). Although this represents a very high transport potential, little can be said about vesicular effective performance because of insufficient knowledge of vesicular biology and biophysics. A frequent observation in the capillary network is attenuations of endothelial cells, which are thinner than the vesicular diameter and devoid of vesicles.