Pet-specific IgG4 levels and the likelihood of symptomatic pet allergy

Published Online: May 6, 2013

An increase in allergen-specific IgG4 (sIgG4) level often accompanies successful allergen immunotherapy. Studies have also suggested that chronic exposure to some allergens may lead to increased sIgG4 that may function as “blocking antibodies” and signal a degree of clinical tolerance.

In a recent study published in The Journal of Allergy and Clinical Immunology: In Practice, Burnett and colleagues report on data from 500 teenage participants in a longitudinal birth cohort and describe the association of dog and cat specific IgE (sIgE), sIgG4, and the ratios of sIgG4/sIgE antibodies to self-reported symptoms when in contact with pets. Serum levels of the pet-specific antibodies were compared between symptomatic and asymptomatic teens.

Compared to asymptomatic participants, those symptomatic upon cat exposure had higher cat sIgE, sIgG4, and lower ratios of sIgG4/sIgE. Those symptomatic after dog exposure had higher dog sIgE and lower ratios of sIgG4/sIgE, but similar levels of sIgG4 compared to asymptomatic participants. Higher cat and dog sIgG4/sIgE ratios were associated with a lower likelihood of reporting allergic symptoms. However, measurement of sIgG4 appeared to add little to the current clinical practice of using sIgE alone to determine the likelihood of clinical allergic responses when in contact with pets.

Based on these data, the authors do not recommend the routine measurement of sIgG4 as a useful supplementary test to sIgE during the diagnostic evaluation of potential pet allergy.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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