A New Digital Method for Counting Mast Cells in Cutaneous Specific Lesions of Mastocytosis: A Series of Adult Cases of Mastocytosis With Clinical-Pathological Correlations.

ABSTRACT: Cutaneous mastocytosis is characterized by the abnormal accumulation of mast cells in the skin. However, mast cell counting is not always easy and reproducible with classical methods. This work aims to demonstrate the reliability, usability, and virtues of a new software used on digital tablets for counting mast cells in cutaneous specific lesions of mastocytosis, to assess differences in mast cell counts between clinical subtypes of mastocytosis in the skin, and to consider the feasibility of applying a diagnostic mast cell count cutoff to urticaria pigmentosa, which is the most frequent form of cutaneous mastocytosis. Using a new digital tablet software that was accessible by multiple observers through its own wireless network and allowed high resolution of the image without data compression, we counted the number of mast cells on slides of patients and control skins immunostained for CD117. We found that our counting method was highly reproducible and that the new software allowed very quick counting. We evidenced strong differences in the mast cell count between most of the clinical subtypes of mastocytosis in the skin. However, when applied to a subset of patients with urticaria pigmentosa, a diagnostic cutoff in the mast cell count lacked sensitivity. Thus, our digital method for counting CD117-immunostained mast cells was highly accurate and was of a significant value for the diagnosis of mastocytosis in the skin. However, some subtypes with low mast cell counts will still require the application of additional diagnostic criteria.

Immunophenotype of pediatric-onset mastocytosis does not correlate with clinical course.

BACKGROUND: Pediatric mastocytosis differs from adult mastocytosis in its presentation and clinical course. However, the data regarding the immunophenotypic characterization of mast cells in children are limited. Our objective was to evaluate the immunophenotype of mast cells in pediatric mastocytosis and correlate it with the clinical course. METHODS: Biopsy specimens of children with cutaneous mastocytosis were retrieved from the institutions of pathology and were stained for CD25, CD2, and CD30. The percentage of mast cells and the staining intensity were correlated with the clinical data. RESULTS: Twenty-five biopsy specimens were included in the study. Patients' average age was 15.4 at presentation and 37.5 months at biopsy performance. Clinical presentations included maculopapular cutaneous mastocytosis in 79% and mastocytoma in 21% of cases. CD25, CD2, and CD30 were positive in 60%, 44%, and 84% of the biopsy specimens, respectively. The staining score was significantly higher for CD30 as compared to those for CD25 and CD2 (P = 0.02). No correlation was found between the immunophenotype and the clinical form or course of disease. CONCLUSIONS: Our results confirm that CD30 is a sensitive marker for pediatric-onset mastocytosis. Nevertheless, its expression does not correlate with clinical subtype or clinical course. The sensitivity of CD25 is higher than that of CD2 in skin lesions.

The efficacy of omalizumab in Cutaneous Mastocytosis: A case series.

BACKGROUND: Mastocytosis describes a heterogeneous group of disorders arising from a clonal proliferation of mast cells. Given the lack of curative treatments for the cutaneous form, there is a significant need for superior therapies. Omalizumab is a recombinant DNA-derived humanized IgG monoclonal antibody that selectively binds to human immunoglobulin E (IgE). It represents a potential treatment for the management of cutaneous mastocytosis, which currently has no standard treatment. METHODS: Two patients were treated with subcutaneous omalizumab 300 mg every 4 weeks. DISCUSSION: Patient 1 experienced 50% reduction in cutaneous infiltration and moderate improvement in pruritus. Patient 2 underwent 90% complete clearance of cutaneous lesions and reported full resolution of pruritus. The median duration of treatment was 24 weeks and time to response was 8 weeks. No significant changes in tryptase levels were observed. Both patients experienced injection site reactions. CONCLUSION: We provide evidence from two cases supporting the efficacy of IgE-mediated therapy in the treatment of cutaneous mastocytosis. Even at a higher-than-standard dose (300 mg vs. 150 mg), the drug was well-tolerated. As we await the results of pivotal clinical trials, omalizumab appears to be a promising treatment option in patients with cutaneous mastocytosis unresponsive to traditional therapies.

Immune response against HtrA proteases in children with cutaneous mastocytosis.

Mast cells play an important role in both, the innate and adaptive immunity, however, clonal proliferation of abnormal mast cells in various organs leads to mastocytosis. A skin variant of the disease, cutaneous mastocytosis (CM) is the most frequent form of mastocytosis in children. HtrA proteases are modulators of important cellular processes, including cell signaling and apoptosis, and are related to development of several pathologies. The above and the observation that mast cells constitutively release the HtrA1 protein, prompted us to investigate a possible involvement of the HtrA proteins in pediatric CM. Levels of the serum autoantibodies (IgG) against the recombinant HtrA proteins (HtrA1-4) in children with CM (n=36) and in healthy controls (n=62) were assayed. Anti-HtrA IgGs were detected using enzyme linked immunosorbent assay (ELISA) and Western-blotting. In the CM sera, levels of the anti-HtrA1 and anti-HtrA3 autoantibodies were significantly increased when compared to the control group, while the HtrA protein levels were comparable. No significant differences in the anti-HtrA2 IgG level were found; for the anti-HtrA4 IgGs lower levels in CM group were revealed. In healthy children, the IgG levels against the HtrA1, -3 and -4 increased significantly with the age of children; no significant changes were observed for the anti-HtrA2 IgG. Our results suggest involvement of the HtrA1 and HtrA3 proteins in pediatric CM; involvement of the HtrA4 protein is possible but needs to be investigated further. In healthy children, the autoantibody levels against HtrA1, -3 and -4, but not against HtrA2, increase with age.

Cutaneous Mastocytosis in Adults and Children: New Classification and Prognostic Factors.

The skin is one of the most frequent tissues affected in patients with mastocytosis, but cutaneous lesions are highly heterogeneous in shape, size, color, number, localization, and distribution. The World Health Organization recognizes 3 subtypes of cutaneous mastocytosis (CM): maculopapular CM (MPCM), diffuse CM, and mastocytoma of skin. An international task force of experts in mastocytosis has recently proposed subdividing MPCM into monomorphic and polymorphic, which could predict the duration of the disease in children. More research is warranted to develop an improved classification of CM that ideally should incorporate robust factors with prognostic impact on disease behavior.

Copper Regulates Maturation and Expression of an MITF:Tryptase Axis in Mast Cells.

Copper has previously been implicated in the regulation of immune responses, but the impact of this metal on mast cells is poorly understood. In this article, we address this issue and show that copper starvation of mast cells causes increased granule maturation, as indicated by higher proteoglycan content, stronger metachromatic staining, and altered ultrastructure in comparison with nontreated cells, whereas copper overload has the opposite effects. In contrast, copper status did not impact storage of histamine in mast cells, nor did alterations in copper levels affect the ability of mast cells to degranulate in response to IgER cross-linking. A striking finding was decreased tryptase content in mast cells with copper overload, whereas copper starvation increased tryptase content. These effects were associated with corresponding shifts in tryptase mRNA levels, suggesting that copper affects tryptase gene regulation. Mechanistically, we found that alterations in copper status affected the expression of microphthalmia-associated transcription factor, a transcription factor critical for driving tryptase expression. We also found evidence supporting the concept that the effects on microphthalmia-associated transcription factor are dependent on copper-mediated modulation of MAPK signaling. Finally, we show that, in MEDNIK syndrome, a condition associated with low copper levels and a hyperallergenic skin phenotype, including pruritis and dermatitis, the number of tryptase-positive mast cells is increased. Taken together, our findings reveal a hitherto unrecognized role for copper in the regulation of mast cell gene expression and maturation.

Cutaneous manifestations in patients with mastocytosis: Consensus report of the European Competence Network on Mastocytosis; the American Academy of Allergy, Asthma & Immunology; and the European Academy of Allergology and Clinical Immunology.

Cutaneous lesions in patients with mastocytosis are highly heterogeneous and encompass localized and disseminated forms. Although a classification and criteria for cutaneous mastocytosis (CM) have been proposed, there remains a need to better define subforms of cutaneous manifestations in patients with mastocytosis. To address this unmet need, an international task force involving experts from different organizations (including the European Competence Network on Mastocytosis; the American Academy of Allergy, Asthma & Immunology; and the European Academy of Allergology and Clinical Immunology) met several times between 2010 and 2014 to discuss the classification and criteria for diagnosis of cutaneous manifestations in patients with mastocytosis. This article provides the major outcomes of these meetings and a proposal for a revised definition and criteria. In particular, we recommend that the typical maculopapular cutaneous lesions (urticaria pigmentosa) should be subdivided into 2 variants, namely a monomorphic variant with small maculopapular lesions, which is typically seen in adult patients, and a polymorphic variant with larger lesions of variable size and shape, which is typically seen in pediatric patients. Clinical observations suggest that the monomorphic variant, if it develops in children, often persists into adulthood, whereas the polymorphic variant may resolve around puberty. This delineation might have important prognostic implications, and its implementation in diagnostic algorithms and future mastocytosis classifications is recommended. Refinements are also suggested for the diagnostic criteria of CM, removal of telangiectasia macularis eruptiva perstans from the current classification of CM, and removal of the adjunct solitary from the term solitary mastocytoma.

Clinical, immunophenotypic, and molecular characteristics of well-differentiated systemic mastocytosis.

BACKGROUND: Well-differentiated systemic mastocytosis (WDSM) is a rare variant of systemic mastocytosis (SM) characterized by bone marrow (BM) infiltration by mature-appearing mast cells (MCs) often lacking exon 17 KIT mutations. Because of its rarity, the clinical and biological features of WDSM remain poorly defined. OBJECTIVE: We sought to determine the clinical, biological, and molecular features of a cohort of 33 patients with mastocytosis in the skin in association with BM infiltration by well-differentiated MCs and to establish potential diagnostic criteria for WDSM. METHODS: Thirty-three patients with mastocytosis in the skin plus BM aggregates of round, fully granulated MCs lacking strong CD25 and CD2 expression in association with clonal MC features were studied. RESULTS: Our cohort of patients showed female predominance (female/male ratio, 4:1) and childhood onset of the disease (91%) with frequent familial aggregation (39%). Skin involvement was heterogeneous, including maculopapular (82%), nodular (6%), and diffuse cutaneous (12%) mastocytosis. KIT mutations were detected in only 10 (30%) of 33 patients, including the KIT D816V (n = 5), K509I (n = 3), N819Y (n = 1), and I817V (n = 1) mutations. BM MCs displayed a unique immunophenotypic pattern consisting of increased light scatter features, overexpression of cytoplasmic carboxypeptidase, and aberrant expression of CD30, together with absent (79%) or low (21%) positivity for CD25, CD2, or both. Despite only 9 (27%) of 33 patients fulfilling the World Health Organization criteria for SM, our findings allowed us to establish the systemic nature of the disease, which fit with the definition of WDSM. CONCLUSIONS: WDSM represents a rare clinically and molecularly heterogeneous variant of SM that requires unique diagnostic criteria to avoid a misdiagnosis of cutaneous mastocytosis per current World Health Organization criteria.

Rush immunotherapy for wasp venom allergy seems safe and effective in patients with mastocytosis.

BACKGROUND: Patients with mastocytosis and wasp venom allergy (WA) may benefit from venom immunotherapy (VIT). However, fatal insect sting reactions have been described in mastocytosis patients despite previous immunotherapy. We investigated the safety and efficacy of (rush) VIT in patients with mastocytosis and WA. OBJECTIVE: To investigate the safety and efficacy of (rush) VIT in patients with mastocytosis and WA. METHODS: We describe nine patients with cutaneous mastocytosis and WA who received VIT. Cutaneous mastocytosis was confirmed by histopathology and systemic mastocytosis was diagnosed according to World Health Organization criteria. VIT was given according to a rush protocol. Given the difference in safety and efficacy of VIT in patients with WA and honeybee venom allergy, we reviewed the literature for VIT with the focus on WA patients with mastocytosis and addressed the difference between patients with cutaneous versus systemic mastocytosis. RESULTS: Nine patients had WA and mastocytosis, of whom six had cutaneous mastocytosis, two combined cutaneous and systemic mastocytosis and one systemic mastocytosis. All patients received rush IT with wasp venom. Most patients had only mild local side effects, with no systemic side effects during the course of VIT. One patient had a systemic reaction upon injection on one occasion, during the updosing phase, with dyspnoea and hypotension, but responded well to treatment. Immunotherapy was continued after temporary dose adjustment without problems. Two patients with a previous anaphylactic reaction were re-stung, without any systemic effects. CONCLUSIONS: VIT is safe in cutaneous mastocytosis patients with WA, while caution has to be made in case of systemic mastocytosis. VIT was effective in the patients who were re-stung.

Assessment of clinical findings, tryptase levels, and bone marrow histopathology in the management of pediatric mastocytosis.

BACKGROUND: The management of children with pediatric mastocytosis poses a challenge. This is because there is limited information as to the application of clinical and laboratory findings and bone marrow histopathology as they relate to medical intervention and communication. OBJECTIVE: We sought to examine clinical aspects of pediatric mastocytosis in relationship to serum tryptase levels and bone marrow pathology to provide practical guidance for management. METHODS: Between 1986 and 2012, 105 children were evaluated at the National Institutes of Health. Organomegaly was confirmed by means of ultrasound. Baseline tryptase levels and at least 1 subsequent tryptase measurement was available in 84 and 37 of these children, respectively. Fifty-three children underwent a bone marrow examination. These data were used to examine relationships between clinical findings, tryptase levels, and marrow histopathology. RESULTS: In patients with high tryptase levels and severe mediator symptoms, all with organomegaly had systemic disease, and none without organomegaly had systemic disease. Serum tryptase levels differed significantly between patients with urticaria pigmentosa and those with diffuse cutaneous (P < .0001) and systemic mastocytosis (P < .0001) and in all 3 categories versus control subjects (P < .0001). Tryptase levels and symptoms decreased over time in most patients, and tryptase levels correlated with bone marrow mast cell burden in patients with systemic mastocytosis (P < .0001). There was a significant relationship between clinical resolution and the percentage decrease in tryptase levels (P = .0014). CONCLUSIONS: The majority of children experienced major or complete disease resolution (57%), whereas the remainder exhibited partial improvement. Organomegaly was a strong indicator of systemic disease. Serum tryptase levels furthered classification and reflected clinicopathologic findings, while sequential tryptase measurements were useful in supplementing clinical judgment as to disease course.

Ablation of human skin mast cells in situ by lysosomotropic agents.

Mast cells are known to have a detrimental impact on numerous types of inflammatory skin diseases such as contact dermatitis, atopic eczema and cutaneous mastocytosis. Regimens that dampen skin mast cell-mediated activities can thus offer an attractive therapeutic option under such circumstances. As mast cells are known to secrete a large array of potentially pathogenic compounds, both from preformed stores in secretory lysosomes (granules) and after de novo synthesis, mere inhibition of degranulation or interference with individual mast cell mediators may not be sufficient to provide an effective blockade of harmful mast cell activities. An alternative strategy may therefore be to locally reduce skin mast cell numbers. Here, we explored the possibility of using lysosomotropic agents for this purpose, appreciating the fact that mast cell granules contain bioactive compounds prone to trigger apoptosis if released into the cytosolic compartment. Based on this principle, we show that incubation of human skin punch biopsies with the lysosomotropic agents siramesine or Leu-Leu methyl ester preferably ablated the mast cell population, without causing any gross adverse effects on the skin morphology. Subsequent analysis revealed that mast cells treated with lysosomotropic agents predominantly underwent apoptotic rather than necrotic cell death. In summary, this study raises the possibility of using lysosomotropic agents as a novel approach to targeting deleterious mast cell populations in cutaneous mastocytosis and other skin disorders negatively influenced by mast cells.

The genetic basis of mast cell activation disease - looking through a glass darkly.

Within the last decade, and in particular since 2012, research has greatly extended our understanding of the molecular basis of systemic mast cell activation disease (MCAD). Initial studies demonstrated that somatic mutations in the tyrosine kinase KIT led to the establishment of a clonal mast cell population. Recent studies, in particular those involving next generation sequencing analyses of advanced systemic mastocytosis, have revealed mutations in additional genes. The respective genes encode proteins for various signaling pathways, epigenetic regulators, the RNA splicing machinery, and transcription factors. Although almost all of the detected mutations are somatic in nature, transgenerational transmission of MCAD appears to be quite common. However, the molecular mechanisms underlying genetic predestination, e.g. germline mutations and the contribution of epigenetic processes, still await identification. The aim of the present review is to present and discuss available genetic findings, and to outline the relationship between adult-onset systemic MCAD and childhood-onset mastocytosis, often termed cutaneous mastocytosis, on the basis of current genetic data. Finally, the implications of increased knowledge of the molecular basis of MCAD in terms of diagnostics and therapy are discussed.

Does the aberrant expression of CD2 and CD25 by skin mast cells truly correlate with systemic involvement in patients presenting with mastocytosis in the skin?

BACKGROUND: Neoplastic mast cells involving the bone marrow (BMMCs) of patients with mastocytosis display an aberrant expression of CD25 and/or CD2 antigens. The aim of this study was to determine the frequency of CD2 and CD25 expression on skin mast cells (sMCs) of patients with mastocytosis in the skin at the early stage of the disease. Furthermore, the usefulness of the phenotypic profile of sMCs for the diagnosis of systemic mastocytosis (SM) was evaluated. METHODS: The 52 adults included in the study were diagnosed with mastocytosis strictly according to the criteria of the World Health Organization. CD117, CD2 and CD25 antigen expression on sMCs was detected by immunohistochemistry. The presence of the KIT D816V mutation in the BM was analyzed using allele-specific PCR. RESULTS: The presence of CD2- or CD25-positive sMCs was detected in 57.1% of cutaneous mastocytosis (CM) and 90.3% of SM cases (p = 0.008). In all mastocytosis patients, CD2 expression on sMCs was more frequent than CD25 expression (67.3 and 38.5%, respectively). Moreover, CD2 expression on sMCs was more frequent in SM than in CM cases (p = 0.02). The presence of one of the aberrant sMC antigens was detected in 84.2% of patients with the KIT D816V mutation in the BM. A positive correlation between densities of CD25- and CD117-positive sMCs was found in SM patients (r = 0.46, p = 0.009). CONCLUSIONS: Although sMCs displayed immunoreactivity for one of the neoplastic antigens in the majority of SM patients, the aberrant CD2 and/or CD25 expression on sMCs is not as indicative of SM as the BMMC immunophenotype.

Spectrum of mast cell activation disorders.

Mast cell (MC) activation disorders present with multiple symptoms including flushing, pruritus, hypotension, gastrointestinal complaints, irritability, headaches, concentration/memory loss and neuropsychiatric issues. These disorders are classified as: cutaneous and systemic mastocytosis with a c-kit mutation and clonal MC activation disorder, allergies, urticarias and inflammatory disorders and mast cell activation syndrome (MCAS), idiopathic urticaria and angioedema. MCs are activated by IgE, but also by cytokines, environmental, food, infectious, drug and stress triggers, leading to secretion of multiple mediators. The symptom profile and comorbidities associated with these disorders, such as chronic fatigue syndrome and fibromyalgia, are confusing. We propose the use of the term 'spectrum' and highlight the main symptoms, useful diagnostic tests and treatment approaches.

Predictors of clinical effectiveness of Hymenoptera venom immunotherapy.

BACKGROUND: Treatment failure during venom immunotherapy (VIT) may be associated with a variety of risk factors, of which the relative importance is unknown. OBJECTIVE: Our aim was to evaluate the association of baseline serum tryptase concentration (BTC), mastocytosis in the skin (MIS) and of other parameters with the frequency of objective systemic reactions during in-hospital sting challenge (SC). METHODS: In this observational retrospective study, we enrolled 1532 patients (1609 cases due to double SC) with established honeybee or vespid venom allergy who had undergone VIT and a subsequent SC. Data were collected on various putative risk factors. Adult-onset MIS and/or a BTC > 20.0 µg/L was defined as clinical indicators of systemic mastocytosis. Relative rates were calculated with logistic regression models. RESULTS: Ninety-eight patients (6.4%) presented with MIS and/or BTC > 20.0 µg/L. 104 cases (6.5%) developed objective generalized symptoms during SC. In the absence of MIS, a BTC ≤ 20 µg/L did not increase the risk for VIT failure. The most important factors associated with a worse outcome were ACE inhibitor medication (OR 5.24, 95% CI 1.83-13.00, P < 0.001), honeybee venom allergy (OR 5.09, 95% CI 3.17-8.15, P < 0.001), systemic allergic reaction during VIT (OR 3.07, 95% CI 1.79-5.14, P < 0.001), and a substantial likelihood to suffer from SM (OR 2.74, 95% CI 1.37-5.22, P = 0.003), whereas a double VIT (OR 0.51, 95% CI 0.27-0.90, P = 0.027) and a longer duration of therapy (OR 0.68 per treatment month, 95% CI 0.50-0.93, P = 0.017) reduced the failure rate. CONCLUSION: The magnitude of therapeutic success correlates with type of venom, duration of therapy, and venom dose. Adult-onset MIS and/or a BTC > 20 µg/L is a significant, albeit not the strongest determinant for VIT failure. According to its odds ratio, ACE inhibitor therapy appears to be associated with the highest risk for VIT failure.

Benign mast cell hyperplasia and atypical mast cell infiltrates in penile lichen planus in adult men.

Introduction. Lichen planus (LP) is a chronic cytokine-mediated disease of possible auto-immune etiology. 25% of men have anogenital manifestations. Erosive penile LP causes a scarring phimosis of the foreskin in uncircumcised men. Mast cells as potent immune modulators have been implicated in a number of autoimmune and chronic inflammatory diseases, but have not been investigated in LP. Material and Methods. Formalin-fixed tissues of 117 circumcision specimens of adult men affected by LP were evaluated for the extent of mast cell and lymphocyte infiltrates, characterized immunohistochemically with antibodies to CD 3, 4, 8, 20, 21, 25, 30, 117c and human mast cell tryptase. Specimens with dense mast cell infiltrates were analyzed for point mutations of the c-kit gene (D816V). Results. Unaffected skin and modified mucosa of foreskins contained ⟨5 mast cells/mm². The inflammatory infiltrate of LP-lesions displayed ⟨15 mast cells/mm² in 33/117 foreskins, 16-40 mast cells/mm² in 22/117 and ⟩40 mast cells/mm² (average 70, range 40-100) in 62/117 foreskins. Lesional mast cells of 29/117 (24%) foreskins showed aberrant CD25-expression and/or spindled morphology, with 11/29 men having erosive LP, 13/29 a lymphocytic vasculitis and 1/28 a systemic mastocytosis. Neither CD30-expression nor c-kit mutations were identified. Atypical mast cell infiltrates in LP correlated with high disease activity, erosive LP and presence of lymphocytic vasculitis Conclusions. Increased mast cells in penile LP, mostly representing a benign hyperplasia/activation syndrome, suggests them as targets for innovative therapy options for symptomatic LP-patients not responding to corticosteroid therapy. Presently, the biological implications of atypical mast cell infiltrates in penile LP are unknown.

Expression of the Basophil-Specific Antibodies 2D7 and BB1 in Patients With Cutaneous Mastocytosis

Background: 2D7 and BB1 are thought to be basophil-specific markers. In this study, we tested both antibodies in different skin and mast cell disorders with the aim of determining whether it was possible to differentiate between benign and aggressive presentations of mastocytosis. Methods: Using the antibodies 2D7, BB1, and c-Kit, we performed an immunohistochemical study of skin biopsy specimens from patients with cutaneous mastocytosis (15 urticaria pigmentosa and telangiectatic macularis eruptive perstans) and liver or bone marrow biopsy specimens from patients with systemic mastocytosis. A basophil leukemia cell line was used as a reference. Peripheral blood basophils from healthy donors were used as controls. Results: We observed intense expression of 2D7 and BB1 in all skin biopsy specimens from patients with cutaneous mastocytosis. Immunostaining of liver and bone marrow specimens from patients with systemic mastocytosis with 2D7 and BB1 antibodies was negative. Specimens from patients with either type of mastocytosis showed similarly strong expression of c-Kit. The basophil cell line showed a 2D7 and a BB1 profile, with intense expression of c-Kit. Peripheral blood basophils exhibited notable immunostaining for 2D7, BB1, and c-Kit. Conclusions: 2D7 and BB1 are expressed in cutaneous mastocytosis, although this expression is lost when mast cell proliferation is systemic, thus reflecting either a different cellular differentiation stage or the presence of basophils in these skin diseases (AU)

Antecedentes: Los anticuerpos 2D7 y BB1 son marcadores específicos para basófilos. En el presente trabajo hemos estudiado el comportamiento de ambos marcadores en mastocitosis cutánea y sistémica, con el objeto de comprobar si las formas cutáneas benignas se podían diferenciar de las sistémicas. Métodos: Hemos realizado inminuhistoquímica de biopsias de 15 pacientes con matocitosis cutánea, empleando los anticuerpos c-Kit, 2D7 y BB1 y hemos comparado el resultado con biopsias hepáticas y de médula ósea de tres pacientes con mastocitosis sistémica frente a los mismos anticuerpos. Empleamos una línea celular de leucemia humana basofílica y basófilos aislados de un donante sano como controles. Resultados: Hallamos un patrón 2D7 y BB1 intensamente positivo en todas las muestras de mastocitosis cutánea y basófilos de donantes sanos. Sin embargo, tanto el anticuerpo 2D7 como BB1 fue negativo en las muestras hepáticas y de médula ósea de mastocitosis sistémica así como en la línea celular de leucemia basofílica. C-Kit se expresó intensamente en todas las muestras. Conclusión: 2D7 y BB1 se expresa en mastocitosis cutánea si bien se pierde cuando los mastocitos proliferan en su forma sistémica. Esto puede reflejar bien una diferenciación celular distinta o bien que los basófilos están presentes en las lesiones cutáneas de mastocitosis (AU)

Rupatadine improves quality of life in mastocytosis: a randomized, double-blind, placebo-controlled trial.

BACKGROUND: Mastocytosis is frequently associated with mast cell-mediated symptoms which require relieving medication. While second generation antihistamines (sgAHs) are the first line therapeutic strategy to treat mast cell mediator-related symptoms, controlled clinical trials on how they improve quality of life have not been performed. METHODS: This randomized, double-blind, placebo-controlled, cross-over trial assessed rupatadine 20 mg daily in the treatment of mastocytosis symptoms in 30 adult patients. Symptoms were assessed by a visual analogue scale (VAS) and symptom specific quality of life questionnaire (ItchyQoL). RESULTS: The mean ItchyQoL total score and VAS symptom score were significantly improved in the rupatadine treatment phase compared with placebo. There were also significant reductions from placebo in the severity of itch, wheal and flare, flushing, tachycardia and headache but not gastrointestinal symptoms. CONCLUSIONS: In this first comprehensive trial of a sgAH in mastocytosis, rupatadine 20 mg daily for 4 weeks significantly controlled symptoms and improved patients' quality of life.

Pimecrolimus induces apoptosis of mast cells in a murine model of cutaneous mastocytosis.

BACKGROUND: Cutaneous mastocytosis (CM) is a common type of mastocytosis. Current treatment of CM is generally symptomatic. Pimecrolimus has been demonstrated as an effective anti-inflammatory drug for the treatment of inflammatory skin diseases, but whether it treats CM remains unknown. METHODS: The murine model of CM was induced by subcutaneous injection of 100 µg/kg recombinant murine stem cell factor (rmSCF) for a total of 17 days in Balb/c mice. Beginning on the 8th day, treatment with pimecrolimus 1% cream or vehicle was performed topically and daily for 10 days. The clinical signs of CM were scored, and pathological analysis was performed with toluidine blue staining and hematoxylin and eosin staining. The in situ apoptotic mast cells (MCs) were studied by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. The cutaneous histamine level was measured by ELISA. RESULTS: In the rmSCF-treated mice, the clinical signs of CM, including erythema, wheal after rubbing lesion skins, and increased thickness of skin, were obvious compared to control mice, and were reduced after pimecrolimus treatment. The numbers of cutaneous MCs and neutrophils were significantly greater in mice with CM than in control mice, and pimecrolimus treatment decreased the numbers of MCs but not neutrophils. Extensive apoptosis of cutaneous MCs was observed in pimecrolimus-treated mice. The cutaneous histamine level was elevated in the mice with CM compared with healthy controls, and was lowered after treatment with pimecrolimus. CONCLUSIONS: Pimecrolimus effectively treats CM by reducing the density of cutaneous MCs and the subsequent histamine production through inducing MCs apoptosis.