Relationship of dog- and cat-specific IgE and IgG4 levels to allergic symptoms on pet exposure.

BACKGROUND

Environmental allergens may induce the generation of allergen-specific IgE (sIgE) and IgG4 (sIgG4). Some studies report an association of sIgG4 to protection against allergic symptoms after exposure to the relevant allergen.

OBJECTIVE

We examined the relationship of dog and cat sIgE and sIgG4 levels to self-reported allergic symptoms on pet contact.

METHODS

Participants 18 years of age in the Detroit Childhood Allergy Study cohort were asked whether they experienced symptoms on exposure to cats and dogs. Serum was assayed for cat and dog sIgE and sIgG4. Geometric means, ratios of cat and dog sIgE, sIgG4, and ratios of sIgG4/sIgE were compared between symptomatic and asymptomatic teens with the use of Wilcoxon rank sum tests. Ratios of sIgG4/sIgE, adjusted for presence of sIgE (≥0.35 kU/mL), were analyzed with logistic regression.

RESULTS

Data on 500 participants were analyzed. Compared with asymptomatic teens, teens symptomatic with cat exposure had higher cat sIgE, sIgG4, and lower ratio of sIgG4/sIgE. Teens symptomatic after dog exposure had higher dog sIgE levels and lower sIgG4/sIgE, but similar levels of sIgG4 compared with asymptomatic participants. Increasing cat and dog sIgG4/sIgE ratios were associated with a lower likelihood of reporting allergic symptoms (cat: adjusted odds ratio, 0.8; 95% CI, 0.6-0.9; dog: adjusted odds ratio, 0.8; 95% CI, 0.7-1.0).

CONCLUSION

sIgG4 levels to cat and dog allergens correlate with lower rates of pet-induced allergic symptoms when interpreted in the context of concomitant sIgE. However, sIgG4 appears to have little utility as an isolated marker to indicate that pet exposure will be well tolerated.