08.05.2020 | Systemische Mastozytose | Übersicht
Venom immunotherapy in patients with mastocytosis
Erschienen in: Allergo Journal | Ausgabe 3/2020
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Patients with primary mast cell (MC) activation syndromes (MCAS) [1, 2] - which include systemic mastocytosis (SM) and clonal or monoclonal MCAS (MMAS) (Tab. 1) - often present with anaphylaxis [3]. Moreover, a clear relationship has been demonstrated between hymenoptera venom anaphylaxis (HVA) and primary MCAS [4]; in fact, hymenoptera is the first cause of anaphylaxis in patients with SM in the absence of skin lesions compatible with urticaria pigmentosa (UP) [5]. An early study by Bonadonna et al. reported an overall frequency of clonal MC disorders in 7.9 % [6] of the patients suffering from life-threatening reactions after bee and/or wasp stings, but a more recent report has suggested that this percentage might be as high as 26 % [7]. Venom immunotherapy (VIT) is the only treatment that can prevent further systemic IgE-mediated reactions in venom allergic patients, and it has proven to be a safe and effective procedure [8]. Here, we review the clinical and biological characteristics of patients with primary MCAS who present with HVA, the diagnostic tests that have been demonstrated to be useful, and the safety and effectiveness of VIT in this subset of patients.
Types of MCAS
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Diagnostic characteristics
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Primary
— Systemic mastocytosis
— Clonal or monoclonal MCAS
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— One major criterion and one minor criterion or at least three minor WHO criteria* are required.
— Only 1 or 2 WHO minor SM criteria* are fulfilled.
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Secondary
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IgE-mediated allergy or other conditions that can activate MCs exist in the absence of neoplasic MCs or KIT mutation.
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Idiopathic
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MCAS criteria are met but neither primary nor secondary causes of mast cell activation are detected.
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*Diagnostic critera of mastocytosis, according to the WHO. Major criteria: multifocal dense infiltrates of MCs (>15 MCs aggregating) detected in BM sections and/or other extracutaneous organ(s) by tryptase-immunohistochemistry or other MC-associated stains. Minor criteria: i) more than 25% of MC are spindle-shaped in MC infiltrates detected in BM sections or other extracutaneous tissue sections OR >25% atypical MC detected in BM smears, ii) detection of a KIT point mutation at codon 816 in BM MCs or other extracutaneous organ(s), iii) expression of CD25 and/or CD2 on mast cells in BM MCs, blood or other extracutaneous tissues, and iv) total serum baseline tryptase concentration persistently > 20 ng/ml (in case of an systemic mastocytosis with associated clonal hematological non-mast cell lineage disease, this criteria is not valid).
BM, bone marrow; MC, mast cell; MCAS, mast cell activation syndrome; SM, systemic mastocytosis; WHO, world health organization
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