Endocrine Abstracts

The allergic sensitization represents an environmental factor for thyroid autoimmunity and highlights a common pathway between autoimmunity and allergy. Elevated IgE levels are connected to hyperthyroid Graves’ disease. The allergic sensitization in thyroid autoimmunity seems mainly to be an associated immune reaction.

Allergic sensitization to 20 aeroallergens and the levels of thyroid hormones and antibodies were studied in 121 patients with Graves’ disease, 104 patients with Hashimoto’s thyroiditis and 65 healthy subjects. AllergyScreen test with quantitative evaluation was applied for the detection of allergic-specific IgE levels. The levels of TSH, FT₄, FT₃ and anti-thyroid peroxidase (TPO), anti-thyroglobulin (Htg) and TSH receptor antibodies were measured.

The house-dust mite II (D2) allergic sensitization was more frequent in thyroid autoimmunity than in controls (odds ratio (OR): 2.97, P<0.002 in Graves’ disease; OR: 3.41, P<0.01 in Hashimoto’s thyroiditis). The allergic sensitizations to alder (T2, OR: 2.85, P<0.03), birch (T₃, OR: 3.27, P<0.03), ragweed (W1, OR: 2.7, P<0.01) and grass-mixture (Gx, OR: 2.58, P<0.04) were higher in Graves’ patients than in those with Hashimoto’s thyroiditis. The mugwort (W6) allergic sensitization was associated with increased levels of TSH receptor antibodies (11.7±13.5 U/l vs 7.9±17.3 U/l, OR: 6.47, P<0.03). The birch (T₃) and the ragweed (W1) allergic specific IgE levels were associated with increased anti-TPO (OR: 3.88, P<0.04) and increased FT₄ (OR: 2.73, P<0.04) in Graves’ disease or lower TSH levels (OR: 8.27, P<0.004) in Hashimoto’s thyroiditis, respectively. The modifying effect of allergic sensitization did not depend on the presence of allergic symptoms.

The results in matching of amino acid sequences demonstrated a high percentage of identities (42–50%) between W1, W6, T₃ aeroallergens and thyroid antigens (TSH receptor, TSH, TPO, Htg).

In conclusion, the role of antigen mimicry between ragweed, mugwort, birch allergens and thyroid antigens may be responsible for the alteration in the levels of thyroid hormones and antibodies.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.