IgE reactivity to α-Gal in relation to Lyme borreliosis.

Background: An association between tick bites, the development of immunoglobulin E (IgE) antibodies to galactose-α-1, 3-galactose (α-Gal) and red meat allergy has recently been reported. Here we wanted to elucidate the relation between tick exposure, IgE antibodies to α-Gal and Lyme borreliosis (LB).

Methods: In the highly LB endemic area of Kalmar County, Sweden, serum samples and health inquiries from 518 blood donors were included. All sera were investigated for multiple IgG anti-Borrelia antibodies using a multiplex assay (recomBead, Mikrogen). In addition, three serially collected sera over a six month period from 148 patients with clinically defined erythema migrans (EM) were included. IgE antibodies against α-Gal were determined using ImmunoCAP (Thermo Fisher Scientific).

Results: In blood donors reporting previous LB (n = 124) IgE to α-Gal was found in 16%, while in donors denying previous LB but with multiple anti-Borrelia antibodies (n = 94; interpreted as asymptomatic LB) 10% were IgE α-Gal-positive. Finally, in donors without Borrelia antibodies denying previous LB (n = 300) 14% showed IgE to α-Gal. No significant difference in proportions among the groups were found. In EM patients, IgE to α-Gal was found in 32/148 (22%) at diagnosis, 31/148 (21%) after two-three months and 23/148 (16%) after six months. A significant reduction of proportion and level of IgE to α-Gal was found between the second and third sample (p<0.01). A positive IgE anti α-Gal was more common among men compared with women both in blood donors and in EM patients (p≤0.01).

Conclusions: IgE to α-Gal reactivity was common in a tick endemic area but showed no significant relation to previous LB. IgE anti-α-Gal reactivity in EM patients peaked within three months of diagnosis of EM, after which it waned indicating that recent tick exposure is of importance in α-Gal sensitization. Furthermore, IgE anti α-Gal was more common in men compared with women.