Single-cell proteomics and transcriptomics capture eosinophil development and identify the role of IL-5 in their lineage transit amplification

The activities, ontogeny, and mechanisms of lineage expansion of eosinophils are less well resolved than those of other immune cells, despite the use of biological therapies targeting the eosinophilia-promoting cytokine interleukin (IL)-5 or its receptor, IL-5Rα. We combined single-cell proteomics and transcriptomics and generated transgenic IL-5Rα reporter mice to revisit eosinophilopoiesis. We reconciled human and murine eosinophilopoiesis and provided extensive cell-surface immunophenotyping and transcriptomes at different stages along the continuum of eosinophil maturation. We used these resources to show that IL-5 promoted eosinophil-lineage expansion via transit amplification, while its deletion or neutralization did not compromise eosinophil maturation. Informed from our resources, we also showed that interferon response factor-8, considered an essential promoter of myelopoiesis, was not intrinsically required for eosinophilopoiesis. This work hence provides resources, methods, and insights for understanding eosinophil ontogeny, the effects of current precision therapeutics, and the regulation of eosinophil development and numbers in health and disease.

TGF-β regulates the stem-like state of PD-1+ TCF-1+ virus-specific CD8 T cells during chronic infection

Recent studies have defined a novel population of PD-1+ TCF-1+ stem-like CD8 T cells in chronic infections and cancer. These quiescent cells reside in lymphoid tissues, are critical for maintaining the CD8 T cell response under conditions of persistent antigen, and provide the proliferative burst after PD-1 blockade. Here we examined the role of TGF-β in regulating the differentiation of virus-specific CD8 T cells during chronic LCMV infection of mice. We found that TGF-β signaling was not essential for the generation of the stem-like CD8 T cells but was critical for maintaining the stem-like state and quiescence of these cells. TGF-β regulated the unique transcriptional program of the stem-like subset, including upregulation of inhibitory receptors specifically expressed on these cells. TGF-β also promoted the terminal differentiation of exhausted CD8 T cells by suppressing the effector-associated program. Together, the absence of TGF-β signaling resulted in significantly increased accumulation of effector-like CD8 T cells. These findings have implications for immunotherapies in general and especially for T cell therapy against chronic infections and cancer.

Author Correction: Commensal-driven immune zonation of the liver promotes host defence

A Correction to this paper has been published: https://doi.org/10.1038/s41586-021-03346-0.

A local regulatory T cell feedback circuit maintains immune homeostasis by pruning self-activated T cells

A fraction of mature T cells can be activated by peripheral self-antigens, potentially eliciting host autoimmunity. We investigated homeostatic control of self-activated T cells within unperturbed tissue environments by combining high-resolution multiplexed and volumetric imaging with computational modeling. In lymph nodes, self-activated T cells produced interleukin (IL)-2, which enhanced local regulatory T cell (Treg) proliferation and inhibitory functionality. The resulting micro-domains reciprocally constrained inputs required for damaging effector responses, including CD28 co-stimulation and IL-2 signaling, constituting a negative feedback circuit. Due to these local constraints, self-activated T cells underwent transient clonal expansion, followed by rapid death ("pruning"). Computational simulations and experimental manipulations revealed the feedback machinery's quantitative limits: modest reductions in Treg micro-domain density or functionality produced non-linear breakdowns in control, enabling self-activated T cells to subvert pruning. This fine-tuned, paracrine feedback process not only enforces immune homeostasis but also establishes a sharp boundary between autoimmune and host-protective T cell responses.

ILC3s control splenic cDC homeostasis via lymphotoxin signaling

The spleen contains a myriad of conventional dendritic cell (cDC) subsets that protect against systemic pathogen dissemination by bridging antigen detection to the induction of adaptive immunity. How cDC subsets differentiate in the splenic environment is poorly understood. Here, we report that LTα1β2-expressing Rorgt+ ILC3s, together with B cells, control the splenic cDC niche size and the terminal differentiation of Sirpα+CD4+Esam+ cDC2s, independently of the microbiota and of bone marrow pre-cDC output. Whereas the size of the splenic cDC niche depended on lymphotoxin signaling only during a restricted time frame, the homeostasis of Sirpα+CD4+Esam+ cDC2s required continuous lymphotoxin input. This latter property made Sirpα+CD4+Esam+ cDC2s uniquely susceptible to pharmacological interventions with LTβR agonists and antagonists and to ILC reconstitution strategies. Together, our findings demonstrate that LTα1β2-expressing Rorgt+ ILC3s drive splenic cDC differentiation and highlight the critical role of ILC3s as perpetual regulators of lymphoid tissue homeostasis.

The Chemoattractant Receptor Ebi2 Drives Intranodal Naive CD4+ T Cell Peripheralization to Promote Effective Adaptive Immunity

Lymph nodes (LNs) play critical roles in adaptive immunity by concentrating in one location the antigens, antigen-presenting cells, and antigen-responsive lymphocytes involved in such responses. Recent studies have revealed nonrandom localization of innate and adaptive immune cells within these organs, suggesting that microanatomical positioning optimizes responses involving sparse cooperating cells. Here, we report that the peripheral localization of LN cDC2 dendritic cells specialized for MHC-II antigen presentation is matched by a similarly biased paracortical distribution of CD4⁺ T cells directed by the chemoattractant receptor Ebi2. In the absence of Ebi2, CD4⁺ T cells lose their location bias and are delayed in antigen recognition, proliferative expansion, differentiation, direct effector activity, and provision of help for CD8⁺ T cell-mediated memory responses, limiting host defense and vaccine responses. These findings demonstrate evolutionary selection for distinct niches within the LN that promote cellular responses, emphasizing the critical link between fine-grained tissue organization and host defense.

Innate and adaptive lymphocytes sequentially shape the gut microbiota and lipid metabolism

The mammalian gut is colonized by numerous microorganisms collectively termed the microbiota, which have a mutually beneficial relationship with their host. Normally, the gut microbiota matures during ontogeny to a state of balanced commensalism marked by the absence of adverse inflammation. Subsets of innate lymphoid cells (ILCs) and conventional T cells are considered to have redundant functions in containment and clearance of microbial pathogens, but how these two major lymphoid-cell populations each contribute to shaping the mature commensal microbiome and help to maintain tissue homeostasis has not been determined. Here we identify, using advanced multiplex quantitative imaging methods, an extensive and persistent phosphorylated-STAT3 signature in group 3 ILCs and intestinal epithelial cells that is induced by interleukin (IL)-23 and IL-22 in mice that lack CD4+ T cells. By contrast, in immune-competent mice, phosphorylated-STAT3 activation is induced only transiently by microbial colonization at weaning. This early signature is extinguished as CD4+ T cell immunity develops in response to the expanding commensal burden. Physiologically, the persistent IL-22 production from group 3 ILCs that occurs in the absence of adaptive CD4+ T-cell activity results in impaired host lipid metabolism by decreasing lipid transporter expression in the small bowel. These findings provide new insights into how innate and adaptive lymphocytes operate sequentially and in distinct ways during normal development to establish steady-state commensalism and tissue metabolic homeostasis.

Suppression of lethal autoimmunity by regulatory T cells with a single TCR specificity

Levine et al. investigate the extent to which regulatory T cells with either a monoclonal T cell receptor (TCR) or random TCR repertoire in place of their developmentally selected specificities maintain TCR-dependent gene expression and immunosuppressive function.

The regulatory T cell (T reg cell) T cell receptor (TCR) repertoire is highly diverse and skewed toward recognition of self-antigens. TCR expression by T reg cells is continuously required for maintenance of immune tolerance and for a major part of their characteristic gene expression signature; however, it remains unknown to what degree diverse TCR-mediated interactions with cognate self-antigens are required for these processes. In this study, by experimentally switching the T reg cell TCR repertoire to a single T reg cell TCR, we demonstrate that T reg cell function and gene expression can be partially uncoupled from TCR diversity. An induced switch of the T reg cell TCR repertoire to a random repertoire also preserved, albeit to a limited degree, the ability to suppress lymphadenopathy and T helper cell type 2 activation. At the same time, these perturbations of the T reg cell TCR repertoire led to marked immune cell activation, tissue inflammation, and an ultimately severe autoimmunity, indicating the importance of diversity and specificity for optimal T reg cell function.

Lymph node stromal cells constrain immunity via MHC class II self-antigen presentation

Non-hematopoietic lymph node stromal cells shape immunity by inducing MHC-I-dependent deletion of self-reactive CD8⁺ T cells and MHC-II-dependent anergy of CD4⁺ T cells. In this study, we show that MHC-II expression on lymph node stromal cells is additionally required for homeostatic maintenance of regulatory T cells (Tregs) and maintenance of immune quiescence. In the absence of MHC-II expression in lymph node transplants, i.e. on lymph node stromal cells, CD4⁺ as well as CD8⁺ T cells became activated, ultimately resulting in transplant rejection. MHC-II self-antigen presentation by lymph node stromal cells allowed the non-proliferative maintenance of antigen-specific Tregs and constrained antigen-specific immunity. Altogether, our results reveal a novel mechanism by which lymph node stromal cells regulate peripheral immunity.

DOI:http://dx.doi.org/10.7554/eLife.04433.001

In vertebrates, the immune response that protects against infection and disease is made up of two systems. The body's first line of defense is the innate immune system that attacks invaders rapidly but indiscriminately. If this fails to stop disease progression, the adaptive immune system is activated. Although the adaptive immune response is relatively slow compared with the innate immune response, it is more deliberate and produces cells that specifically target and destroy the pathogen or diseased cells present. The adaptive immune system also produces cells that ‘remember’ the pathogen so that it can be destroyed more quickly if it invades again.

A special type of white blood cell, called a T cell, is key to the adaptive immune response. To activate T cells, fragments of molecules that provoke an immune response—called antigens—must be bound to a ‘major histocompatibility complex’ (MHC) and presented to these cells. This process often occurs in lymph nodes, organs that filter the fluid moving from the body's tissues back into the blood.

Particular cells in the lymph node, called lymph node stromal cells, are essential for the organ's structure; recently, these cells have also been found to play roles in regulating the immune response. For example, lymph node stromal cells can help to destroy self-reactive T cells that attack the host's normal, healthy cells. In addition, some types of lymph node stromal cells produce major histocompatibility complexes, although exactly what these complexes do on these cells was unknown.

Baptista, Roozendaal et al. investigated the role of the major histocompatibility complexes expressed by lymph node stromal cells by transplanting mutant cells that could not produce these complexes into otherwise normal mice. In these mice, T cells became more activated than normal and the transplant was rejected after several weeks.

On further investigation, Baptista, Roozendaal et al. discovered that the major histocompatibility complexes produced by the lymph node stromal cells help to maintain an active population of regulatory T cells. These cells are responsible for shutting down the immune response. This work therefore improves our understanding of how the immune response is regulated and could help to develop new strategies for preventing donor organs being rejected after transplantation.

DOI:http://dx.doi.org/10.7554/eLife.04433.002

Expansion of circulating Foxp3+)D25bright CD4+ T cells during specific venom immunotherapy

BACKGROUND

Venom immunotherapy (VIT) induces long-lasting immune tolerance to hymenoptera venom antigens, but the underlying mechanisms are not yet clarified. Regulatory T cells are thought to play an important role in allergic diseases and tolerance induction during specific immunotherapy.

AIM

Characterize longitudinally the impact of VIT on the pool of circulating regulatory T cells.

METHODS

Fourteen hymenoptera venom-allergic patients with severe reactions (grades III-IV) were studied before, 6 and 12 months after starting ultra-rush VIT. Freshly isolated peripheral blood mononuclear cells were surface stained with a panel of markers of T cell differentiation and intracellularly for CTLA-4 and Foxp3 and analysed by flow cytometry. foxp3 mRNA was quantified by real-time PCR. VIT responses were assessed by measuring specific IgG4 and IgE levels. Eleven individuals with no history of insect venom allergy were studied as controls.

RESULTS

VIT induces a significant progressive increase in both the proportion and the absolute numbers of regulatory T cells defined as CD25bright and/or Foxp3+ CD4+ T cells. These changes are not related to alterations in the expression of activation markers or imbalances in the naïve/memory T cell compartments. foxp3 mRNA levels also increased significantly during VIT. Of note, the increase in circulating regulatory T cell counts significantly correlates with the venom-specific IgG4/IgE ratio shift.

CONCLUSION

VIT is associated with a progressive expansion of circulating regulatory T cells, supporting a role for these cells in tolerance induction.

[Plantar hidradenitis]

Tender, plantar nodules occurring in pediatric patients can be associated to different clinical entities, despite similar morphological features, therefore dermatopathology is the best technique for the definitive diagnosis. We describe the case for a 12-year-old patient with tender, red nodules on the left sole 3 days in duration, and with moderate functional disability. The onset of the lesions was preceded by low fever, and occurred 6 days after hepatitis B vaccination (Engerix B). The clinical diagnoses were juvenile plantar erythema nodosum, insect bites, pressure urticaria and plantar hidradenitis; Laboratory and radiographic studies, as well as microscopic examination of a skin biopsy specimen, were performed. The lesions resolved spontaneously in about 10 days, without recurrence after a year. A skin biopsy specimen revealed dense neutrophilic infiltrate surrounding and involving eccrine glans with abscess formation at the dermal-hypodermal junction. The diagnosis of idiopathic plantar hidradenitis was made. We discuss this entity, recently described by Stahr et al, and other erythematous plantar nodules in the pediatric age.

[Leprosy. Comparative study of old and new patients]

Leprosy represented, until a few decades ago, an important public health problem in mainland Portugal. According to the data of the General Directorate of Primary Health Care, the incidence and prevalence rates of the disease have been decreasing progressively and in a significant way during the last years. In view of the fact that it is an endemic disease in regression, we decided to estimate if there were significative changes in the clinical manifestations of the new cases. Therefore, we carried out a comparative study based on the clinical data of 18 patients (13 males and 5 females) with Leprosy who were being followed up in the Dermatology Clinics of Coimbra University Hospital. We differentiated two groups: patients with the diagnosis of the disease before 1990 (old patients), and those diagnosed after 1990 (new patients). The first group had only 8 subjects while the second group had the other 10. We recorded the patients' age, sex, nationality and residence, age at the onset of the disease, number of cases that began before the age of 20, clinical manifestations (according to Ridley and Jopling's classification), and the presence of incapacity determined by the consequences of the disease. We carried out the Student's-t test to appreciate some of the study parameters. We verified that the old patients were on average 11 years younger than the new patients. Leprosy in new patients occurred 11 years later than in the old patients and this difference was statistically significant after the Student's-t test (p < 0.05). Almost one half of the new cases (4 patients in 10) were possible cases of leprosy brought from Brazil, while all the old individuals had an autochthonous origin. The multibacillary forms were predominant in both groups, representing 89% of all patients. The frequency of handicaps was similar in both groups. Although it is based on a small number of patients, our study suggests that the clinical and epidemiological manifestations of leprosy have been changing significantly in the last years and that the changes observed in the form of presentation of the new cases are consistent with the present epidemiological situation. Our study also seems to suggest an increase in the importance of leprosy imported by immigrants from leprosy endemic countries. We point out that this phenomenon, as in the case of AIDS, can theoretically create the conditions for a recrudescence of leprosy, as currently observed with tuberculosis.

[The blue rubber bleb nevus syndrome or Bean's syndrome. A rare cause of digestive hemorrhage]

A 71-year-old male who had previously suffered from chronic alcoholism was admitted to the Internal Medicine Service of Coimbra Hospital Center in January 1996 due to asthenia, loss of weight, icterus and abdominal pain, clinical features that had begun six months before admittance to hospital. A physical examination revealed that, in addition to icterus, the patient presented multiple hemangiomas of 1 to 5 cm in diameter, located in the oral cavity, neck, breast and left axilla. These lesions were bluish, elevated and with a rubber-nipple consistency, and had been developing for about 15 years. Subsequent examination revealed normocytic normochromic anemia, cholestatic icterus and the existence of a gastrointestinal hemangioma located in the esophagus. Excisional biopsy of an element proved that it was cavernous hemangioma. A subsequent angio-scintigraphy indicated other aspects suggestive of deep hemangiomas located in the legs, face and cervical region. The authors had the opportunity of examining other members of the patient's family, who apparently did not exhibit similar lesions. They concluded that it was a case of blue rubber bleb nevus syndrome (BRBNS), probably in its sporadic form. Treatment was essentially conservative and the patient is well.

[A skin lymphoepithelial tumor (skin lymphadenoma)]

The study of a case of cutaneous lymphadenoma and a literature review allowed us to verify that, in contrast to immunohistochemical findings, clinical and histological dates are basically reproducible. Accordingly the eccrine or hair follicle natures of the pleonasm cannot be either excluded or confirmed. The initial terms "cutaneous lympho-epithelial tumor" or "epithelial lymphohistiocytic tumor" seem more suitable than that of "cutaneous lymphadenoma" to describe this peculiar skin neoplasm.

Verrucous cyst

A verrucous cyst is an unusual, histopathologically distinctive, epidermoid cyst characterised by verrucous changes in its wall. We report two cases of verrucous cysts in different patients, one on the back and the other on the cheek. Clinically, the lesions were thought to represent an epidermoid cyst and a basal cell carcinoma, respectively. Histologically, we found in both cases an intradermal epidermoid cyst lined by a stratified squamous epithelium with focal cytopathogenic viral changes, consisting of papillomatosis, ortho- and parakeratosis, and hypergranulosis. One case also showed, within the squamous areas of the hyperplastic epithelium, occasional squamous eddies. These histopathological features support the diagnosis of verrucous cyst, which may represent a manifestation of human papillomavirus infection. This virus may induce cyst formation or just infect a pre-existing one.

Childhood cutaneous mucinosis

A case of childhood cutaneous mucinosis is described. This is a clinical condition that is rarely seen and has only recently been included in the group of primary mucinosis.

Menkes' kinky hair syndrome: ultrastructural cutaneous alterations of the elastic fibers

Menkes' kinky hair syndrome is associated with the defective functioning of several copper-dependent enzymes due to impaired copper absorption, transport, or metabolism. Lysyl oxidase is a copper-requiring enzyme that catalyzes the oxidative deamination of lysyl residues linking two adjacent chains of tropoelastin polypeptides into an insoluble network. Elastin of the connective tissue is the responsible protein for the elastic properties of the skin. We report transmission electron microscopy findings concerning elastic fiber alterations of the skin in three patients with Menkes' syndrome. The reticular dermis showed marked changes in the elastic fibers with a paucity of the central amorphous component while retaining normal microfibrillary material. These ultrastructural observations, to the best of our knowledge, are reported for the first time in skin from these patients and may be readily interpreted in terms of a specific biochemical defect in elastogenesis.

Sebaceous adenitis

A 32-year-old man had an asymptomatic erythematous, annular and circinate eruption on the face for 2 months. Histologic examination revealed sebaceous lobules surrounded by a lymphomonocytic infiltrate and some areas of necrotic sebocytes. The lesions healed without treatment in 1 month. These clinical features can be observed in "neutrophilic sebaceous adenitis," recently described by Renfro et al. The most striking abnormality is the nearly exclusive perisebaceous distribution of the dermal cellular infiltrate with inflammatory cell permeation of the sebaceous epithelium.

Neonatal lupus erythematosus in an infant with Turner syndrome

Neonatal lupus erythematosus (NLE) is characterized by transient, annular cutaneous lesions, congenital heart block, and a variety of systemic or hematologic abnormalities. We describe a white infant girl with onset of skin lesions on the face and scalp at 4 days of age. At age 4 weeks she had generalized, erythematous, scaly, annular skin lesions that underwent spontaneous regression at age 5 months. Her mother had no cutaneous or other lesions, but complement examinations revealed the presence of anti-Ro(SSA) and anti-La(SSB) antibodies, and absence of anti-Sm and anti-RNP antibodies. Karyotyping revealed Turner syndrome (TS) with 45,XO sex chromosome constitution. Ro(SSA) and La(SSB) antibodies were found, and direct immunofluorescence testing on healthy skin was positive. At age 5 months, follow-up immunologic examination of the infant had normal results but the mother still had anti-Ro(SSA) and anti-La(SSB) antibodies. We believe that this is the first reported case of NLE in association with TS.

Tubular apocrine adenoma with eccrine and apocrine immunophenotypes or papillary tubular adenoma?

A case of papillary tubular adenoma is reported. On microscopic examination the lesion, located on the scalp, showed a tubular-branching pattern, opening on the skin surface, and features of decapitation secretion. Immunohistochemical evidence of both eccrine and apocrine differentiation was found. This case, which on a clinicopathological basis alone could be classified as tubular apocrine adenoma, illustrates the difficulties in contrasting the latter to its eccrine counterpart (papillary eccrine adenoma) and suggests that the terms papillary tubular adenoma or tubulopapillary hidradenoma more accurately describe these lesions.

Dermal cylindroma. An immunohistochemical study of thirteen cases

Thirteen dermal cylindromas (DC) have been studied immunohistochemically using a panel of antibodies that stain different portions of normal eccrine and apocrine glands. Distinct staining patterns were found in the different cell populations of the tumor. Although the expression of cytokeratins (CK) 19 and 1/10/11 in occasional duct structures could indicate excretory (ductal) differentiation, a link between DC and apocrine secretory coil is suggested by the expression of alpha-1-antichymotrypsin, lysozyme, human milk factor globulin 1, alpha smooth muscle actin (1A4), and CK 8 and 18. The presence of intermingled S-100 protein-, HLA DR-, and CD1a-positive cells argues for the existence of Langerhans cells within the neoplasm. DC shares epithelial membrane antigen, carcinoembryonic antigen, mucin-like carcinoma-associated antigen (B12), laminin, collagen IV, fibronectin, and CD34(QBEND/10) expression with both eccrine and apocrine glands.

[Leukocytoclastic vasculitis. Review of 51 cases]

Leukocytoclastic vasculitis (L.V.) is a polymorphous inflammatory dermatosis, characterized clinically by palpable purpura of the lower legs and, histologically by fibrinoid change in the small dermal vessels as well a polymorphonuclear infiltrate and nuclear dust. Fifty one cases (33 females and 18 males) of histologically confirmed L.V., seen at the Dermatologic Clinic, University Hospital of Coimbra, are reviewed. The most common type of skin lesions found were palpable purpura (80%), erythematous papules, vesicles and bullae (45%). Systemic manifestations occurred in 32 patients (63%), predominantly fever (33%), arthralgias (27%), malaise (18%) and gastro-intestinal pain (10%). The most frequent laboratory abnormality was a high E.S.R. found in 80% of the patients tested. Possible causative agents could be identified in 37 patients (73%) and included drugs in 12 patients (24%), drugs and infections in 16 (31%) and infection in 3 (6%). Three patients had malignancies and 2 had rheumatoid arthritis. The course of the disorder was acute in 25 cases (49%), recurrent in 14 (27%) and chronic in 10 (20%). The majority of patients (61%) were treated with systemic corticosteroids.

[Macrocheilitis and Melkersson-Rosenthal syndrome. Review of 19 cases]

Melkersson-Rosenthal syndrome is an uncommon condition of unknown cause. The classical triad includes recurrent orofacial oedema involving predominantly the lips (macrocheilitis), intermittent peripheral facial palsy and scrotal tongue. Some authors consider Miescher's cheilitis as a monosymptomatic form of the syndrome. Nineteen cases (11 females and 8 males) of macrocheilitis seen at the Dermatologic Clinic, University of Coimbra, between 1966 and 1992, are reviewed. The complete triad of signs was present only in 4 patients (21%) and two features of the classic triad in 3 (16%) (macrocheilitis and lingua plicata in two; macrocheilitis and facial palsy in one). Twelve patients had only recorrent or persistent orofacial swelling. All 19 patients had macrocheilitis. Less commonly, the check, nose, forehead, eyelid, chin and buccal mucosa were also involved. Peripheral facial paralysis was present in 5 cases (26%), and scrotal tongue occurred in 6 (32%). Lip biopsies, performed in 17 patients, revealed the typical pathologic picture of granulomatous cheilitis only in 8 cases. Systemic corticosteroids and clofazimine were the most efficacious treatment.

Congenital sensory neuropathy with anhidrosis

A 6-year-old girl had congenital sensory neuropathy with anhidrosis (CSNA), one of the five variants of a group of very rare genetic disorders of the peripheral nervous system--hereditary sensory neuropathies (HSN). Clinical, laboratory, and physiopathologic aspects are discussed. Dermatologic findings of anhidrosis and self-mutilation suggest the diagnosis.

Monoclonal antibody Ber EP4 distinguishes basal-cell carcinoma from squamous-cell carcinoma of the skin

Twenty-two cases of basal-cell carcinoma (BCC) and 21 cases of squamous-cell carcinoma of the skin (SCC) were stained for Ber EP4 using indirect immunofluorescence and avidin-biotin-peroxidase techniques. The results showed that all BCCs were diffusely and intensely labeled, whereas none of the SCCs expressed Ber EP4, irrespective of their histological type or grade of differentiation. This difference may prove useful in (a) histologically differentiating between these two neoplasms; and (b) in clarifying the histogenesis of neoplasms considered to be intermediate between BCC and SCC, or derived from BCC. In addition, because significant differences between the staining of hair follicles and BCC were noted, evaluation for Ber EP4 expression could assist in distinguishing between BCC and hair follicles in Mohs micrographic sections.

Experimental studies on the mechanisms of tiaprofenic acid photosensitization

Red blood cell lysis and histidine degradation, photosensitized by tiaprofenic acid (TIA), were investigated. Photohaemolysis was markedly enhanced in oxygenated solutions, but was also intense in the presence of nitrogen. Photohaemolysis was inhibited by butylated hydroxyanisole and reduced glutathione, but was unaffected by sodium azide, superoxide dismutase and mannitol. The TIA-induced photo-oxidation of histidine was greatly enhanced in the presence of oxygen and almost completely inhibited in solutions bubbled with nitrogen. Sodium azide, butylated hydroxyanisole and reduced glutathione inhibited the photodegradation of histidine. Phototoxicity to histidine was unaffected by mannitol and superoxide dismutase. The overall results suggest that molecular mechanisms involving free radicals and singlet oxygen are responsible for TIA-photosensitized reactions. These two in vitro models (photohaemolysis and histidine degradation) represent different mechanisms of phototoxicity, but complement one another in the investigation of potential phototoxic substances.

Trichilemmal carcinoma: review of 8 cases

Clinical and histological data from 8 trichilemmal carcinomas are reviewed. The tumors occurred mainly on sun-exposed skin of the face of elderly people as small solitary, frequently ulcerated nodules. Histologically, they consisted of multilobulate, infiltrative growths, connected to the epidermis and pilosebaceous structures and showing features reminiscent of the outer root sheath of the hair follicle. The presence of lobules of clear, glycogen-rich cells with peripheral palisading, hyaline basement membranes, trichilemmal keratinization, and abortive follicular sheaths and the absence of ductal or acinar differentiation allow distinction from other clear cell tumors of the skin. Although the histological picture suggests a high-grade malignant neoplasm, trichilemmal carcinoma has an indolent course. No recurrence or metastases have been observed.

Photosensitivity to piroxicam: absence of cross-reaction with tenoxicam

We studied 2 groups of patients. One group of 10 patients had a photosensitive eruption to piroxicam. Another group of 24 patients had positive patch test reactions to thimerosal and thiosalicylic acid and had never taken piroxicam or tenoxicam. Patients were patch tested with thimerosal 0.1% pet., thiosalicylic acid 0.1% pet., salicylic acid 2.0% pet., piroxicam 1 and 5% pet. and tenoxicam 1 and 5% pet. Photopatch tests were also performed with piroxicam and tenoxicam. All 10 patients with photosensitivity to piroxicam had positive patch tests to thimerosal and thiosalicylic acid and 9 of them had positive photopatch tests to piroxicam. 20 out of 24 patients with positive patch tests to thiosalicylic acid also had positive photopatch tests to piroxicam. All the patients tested with salicyclic acid were negative. Out of the 29 patients with positive photopatch tests to piroxicam, none reacted to tenoxicam. In countries with a high incidence of contact sensitivity to thimerosal/thiosalicylic acid, the use of piroxicam should be avoided and replaced by tenoxicam, a drug without reported photosensitivity.

Desmoplastic trichilemmoma

Seven cases of desmoplastic trichilemmoma (DT), a recently described pseudomalignant variant of trichilemmoma, are reviewed. The tumor generally occurs in men after the fifth decade of life and presents as a small solitary nodule on the face. It is frequently misdiagnosed clinically as a basal cell carcinoma or a papilloma. Histologically DT displays a superficial lobular growth arranged about a central prominent desmoplastic stroma. At the periphery, the tumor lobules show the typical features of trichilemmoma. In contrast, at the center the cells assume a more random pattern of cords and strands traversed by the hyaline stroma, mimicking invasive carcinoma. The tumor's architectural pattern, in particular the perilobular hyaline mantle, enables DT to be differentiated from basal cell carcinoma and malignant trichilemmoma. Immunohistochemical analysis failed to demonstrate human papilloma virus (HPV), epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), and alpha-lactalbumin in tumor epithelium. Keratin was expressed by the central pseudoinvasive epithelial cords. Neither factor XIIIa nor keratin expression was found in the stromal cells, which stained only for vimentin. These findings suggest that DT is not an HPV-induced epithelial proliferation and that the stroma is not the result of degenerative changes in tumor epithelium. Instead, there appears to be a fibroblast-mediated, dendrocyte-independent, stromal reaction producing this appearance.

[Dermal nerve sheath myxoma. (Neurothekeoma)]

A 59-year-old male presented with a painful nodule on the interscapular area of 20 year duration. The microscopic examination showed a myxomatous lobulated tumor composed of dendritic fusiform cells with some epithelioid and multinucleated cells typical of a nerve sheath myxoma. Immunohistochemical analysis demonstrated reactivity for S100 protein. Neither factor XIIIa nor epithelial membrane antigen (EMA) expression was found in the tumor cells. These findings suggest a schwannian origin for this tumor.

[Peranal ulcers caused by ergotamine-containing suppositories]

Perianal ulcerations caused by suppositories application is an exceptional situation. We describe a 64 years old female with recurrent painless perianal ulcerations evoluting from 14 months. She medicates herself daily, since 8 to 10 years, with ergotamine tartarate suppositories, for the treatment of migraine. The diagnosis of ulcerated cutaneous drug reaction induced by ergotamine tartarate was confirmed by the complete healing of the lesions after stopping this medication and by their recurrence after the reintroduction of the treatment. These ulcerations are probably due to vasospasm of regional arterioles.

Nucleolar organizer regions argyrophilic associated proteins in cutaneous melanocytic lesions

We applied a simple silver staining technique to visualize nucleolar organizer regions associated proteins (AgNORs) for the study of 47 melanocytic lesions (20 malignant melanomas, 5 dysplastic nevi, 4 Spitz nevi, 2 Reed and Gartman's fusiform nevi and 16 melanocytic nevi). A statistically significant difference existed between the numbers of AgNORs per cell in benign and malignant lesions as a group. However, some overlapping counts were found, limiting the usefulness of the technique in differentiating benign from malignant lesions in individual cases.

[Inflammatory variable epidermal naevus (atypical I.L.V.E.N.? A new entity?) (author's transl)]

The authors report a case of two sisters, having one of them left hemiatrophy, with congenital verrucose lesions, in plaques and lineary, bilateral, in extremities, presenting bouts of inflammatory extensive evolution (mostly on the atrophic side), with spontaneous resolution. Histologically the lesions match with those of Nevil's. The authors discuss the nosologic data with that of Nevil's, with epidermic nevus of Solomon and with variable erythrokeratodermis.