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Clinical & Experimental Allergy

An increase in serum tryptase even below 11.4 ng/mL may indicate a mast cell-mediated hypersensitivity reaction: a prospective study in Hymenoptera venom allergic patients

Authors

  • M. Borer-Reinhold,

    1. Allergiestation, Medizinische Klinik, Spital Netz Bern Ziegler, Bern, Switzerland
    2. Allergologisch-Immunologisch Poliklinik, Klinik für Rheumatologie, Immunologie und Allergologie, Universitätspital Bern, Bern, Switzerland
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  • G. Haeberli,

    1. Allergiestation, Medizinische Klinik, Spital Netz Bern Ziegler, Bern, Switzerland
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  • M. Bitzenhofer,

    1. Allergiestation, Medizinische Klinik, Spital Netz Bern Ziegler, Bern, Switzerland
    2. Allergologisch-Immunologisch Poliklinik, Klinik für Rheumatologie, Immunologie und Allergologie, Universitätspital Bern, Bern, Switzerland
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  • P. Jandus,

    1. Allergiestation, Medizinische Klinik, Spital Netz Bern Ziegler, Bern, Switzerland
    2. Allergologisch-Immunologisch Poliklinik, Klinik für Rheumatologie, Immunologie und Allergologie, Universitätspital Bern, Bern, Switzerland
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  • O. Hausmann,

    1. Allergiestation, Medizinische Klinik, Spital Netz Bern Ziegler, Bern, Switzerland
    2. Allergologisch-Immunologisch Poliklinik, Klinik für Rheumatologie, Immunologie und Allergologie, Universitätspital Bern, Bern, Switzerland
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  • M. Fricker,

    1. Allergologisch-Immunologisch Poliklinik, Klinik für Rheumatologie, Immunologie und Allergologie, Universitätspital Bern, Bern, Switzerland
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  • A. Helbling,

    1. Allergiestation, Medizinische Klinik, Spital Netz Bern Ziegler, Bern, Switzerland
    2. Allergologisch-Immunologisch Poliklinik, Klinik für Rheumatologie, Immunologie und Allergologie, Universitätspital Bern, Bern, Switzerland
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  • U. Müller

    Corresponding author
    • Allergiestation, Medizinische Klinik, Spital Netz Bern Ziegler, Bern, Switzerland
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Correspondence:

Prof. Ulrich Müller, Allergiestation, Medizinische Klinik, Spital Netz Bern Ziegler, Morillonstrasse 79-91, CH-3007 Bern, Switzerland.

E-mail: ulrich.mueller@spitalnetzbern.ch

Summary

Background

During a systemic hypersensitivity reaction (SR), an increase in serum tryptase compared to the baseline value is an indicator of mast cell activation, most often due to an IgE-mediated mechanism.

Objective

To study the relevance of an increase in serum tryptase below the upper normal value of 11.4 ng/mL.

Methods

Serum tryptase levels were measured in 35 patients with Hymenoptera venom hypersensitivity before and during venom exposure. Of these, 20 developed SR to stings or following venom injections during immunotherapy (reactors), while 15 tolerated reexposure to stings or venom injections during immunotherapy without SR (non-reactors). Serum tryptase was estimated at 2, 5 and 24 h after exposure and was compared to a baseline value obtained before or at least 72 h after exposure.

Results

Considering circadian variation of serum tryptase, a relative increase to ≥135% of the baseline value (relative delta bound) was defined to indicate mast cell activation. Such an increase was observed in 17 of 20 reactors (85%), but none of 15 non-reactors. A serum tryptase of ≥11.4 ng/mL following venom exposure was observed in eight of the 20 reactors (40%) and 2 (13.3%) of the 15 non-reactors. Both these non-reactors also had an elevated baseline serum tryptase.

Conclusions and Clinical Relevance

Serum tryptase values obtained during a suspected hypersensitivity reaction must always be compared to a baseline value. A relative tryptase increase to ≥135% of the baseline value during a suspected hypersensitivity reaction indicates mast cell activation even below 11.4 ng/mL.

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