Elderly people more prone to insect sting anaphylaxis, probably due to elevated tryptase

This study included 274 patients who were diagnosed with honeybee or wasp venom allergy.

Sting reaction severity increased with increased age and tryptase levels (P = 0.001 and P = 0.0003, respectively).

There was not only a general increment in tryptase levels in elderly people but also a continuous increase in tryptase concentrations even below the cut-off (11.4 mug/l) with increasing age.


A yellow jacket wasp with a typical narrow waist (left) and a honey bee with a fat hairy "fuzzy" body (right). Image source: Wikipedia 1, 2, GNU Free Documentation License.

Serum tryptase is a risk factor for severe anaphylactic reaction to hymenoptera stings. This is the first evidence that basal serum tryptase levels increase continuously with age. Tryptase is an indicator for either increased mast cell load or reactivity this can at least partly be responsible for the observed aggravated allergic reactions in elderly people.

As those patients are at increased risk for life-threatening anaphylactic reactions, it should be considered to adjust VIT in elderly patients with elevated tryptase levels as recommended for patients with mastocytosis by increasing venom doses during VIT and by considering its life-long continuation.

References:
Basal serum tryptase as risk assessment for severe Hymenoptera sting reactions in elderly. Guenova E, Volz T, Eichner M, Hoetzenecker W, Caroli U, Griesinger G, Burow G, Mitev V, Biedermann T. Allergy. 2010 Feb 1. [Epub ahead of print]

Tryptase levels as an indicator of mast-cell activation in systemic anaphylaxis and mastocytosis. NEJM, 1987.