Abstract
Diagnosis of mast cell activation disease (MCAD), i.e. systemic mastocytosis (SM) and idiopathic systemic mast cell activation syndrome (MCAS), usually requires demonstration of increased mast cell (MC) mediator release. Since only a few MC mediators are currently established as biomarkers of MCAD, the sensitivity of plasma heparin level (pHL) as an indicator of increased MC activation was compared with that of serum tryptase, chromogranin A and urinary N-methylhistamine levels in 257 MCAD patients. Basal pHL had a sensitivity of 41% in MCAS patients and 27% in SM patients. Non-pharmacologic stimulation of MC degranulation by obstruction of venous flow for 10 minutes increased the sensitivity of pHL in MCAS patients to 59% and in SM patients to 47%. In MCAS patients tryptase, chromogranin A, and N-methylhistamine levels exhibited low sensitivities (10%, 12%, and 22%, respectively), whereas sensitivities for SM were higher (73%, 63%, and 43%, respectively). Taken together, these data suggest pHL appears more sensitive than the other mediators for detecting systemic MC activity in patients with MCAS. The simple, brief venous occlusion test appears to be a useful indicator of the presence of pathologically irritable MCs, at least in the obstructed compartment of the body.
Highlights
Systemic mast cell activation disease (MCAD) denotes a group of primary mast cell (MC) disorders characterized by aberrant release of variable subsets of MC mediators due to certain sets of genetic mutations sometimes leading to accumulation of dysfunctional MCs in potentially any organs and tissues [1, 2]
Basal plasma heparin level (pHL) had a sensitivity for indicating increased MC activation of 41% in mast cell activation syndrome (MCAS) patients and 27% in systemic mastocytosis (SM) patients (Table 5)
Our data reveal that elevated pHL is a useful indicator of increased systemic MC activation
Summary
Systemic mast cell activation disease (MCAD) denotes a group of primary mast cell (MC) disorders characterized by aberrant release of variable subsets of MC mediators due to certain sets of genetic mutations sometimes leading to accumulation of dysfunctional MCs in potentially any organs and tissues [1, 2]. According to current proposed classifications of MCAD [1,3,4], the traditionally recognized rare variant termed systemic mastocytosis (SM) is characterized by specific constitutively activating somatic mutations in exon 17 of the tyrosine kinase KIT and immunohistochemical findings (known as the World Health Organization (WHO) criteria) [5]. Increased level of the mediator or its metabolites Tryptase level in blood > 20 ng/ml. SM: ~ 80–85% ([16]; further references therein); 77% [39] MCAS: 8% [40]; 22% [41]; 0% [42, 43]; 21% [39]; 33% [44] SM: ~ 50% [30]; 71% [57]; 81% [16]; 76% [39]; MCAS: 0% [42, 46]; 95% [47]; 18% [39]; 10% [44] SM: 0% to 34% [48, 49] MCAS: 0% [49] SM: ~ 50% [51]; 44% [52] SM: 94% [57]; 100% [53]; 62% [56]; MCAS: 75% [42], 68% [35]
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