Background:
Lipocalins form a protein family with great functional similarities. Specifically, they absorb hydrophobic ligands, often complexed with iron, into their molecular pocket, and thereby act bacteriostatic. Accordingly, human lipocalin-2 (LCN2) is an acute phase protein involved in immune defense. Allergics harbor significantly lower LCN2 levels¹, in parallel they suffer from intracellular micronutritional deficiencies, especially of iron².

Aim:
To study:

1. whether the loading of lipocalins may determine why some animal lipocalins act as allergens, and
2. whether loaded ligands may turn lipocalins tolerogenic.

Results:
The lipocalin beta-lactoglobulin (BLG), best known from cow´s milk, acted as allergen only in its empty form^3,4. However, BLG complexed with ligands occurred in cow stable dust and contributed to the allergy protective effect of farms⁵. We developed a lozenge using BLG as a Trojan horse to carry micronutrients to immune cells of allergics. In clinical double-blind placebo-controlled⁶ and provocation trials in pollen and house dust mite allergics we demonstrated that with the BLG lozenge micronutritional deficiencies can be corrected. This is associated with a significant symptom relief.

Conclusion:
We propose that spiking of lipocalins with nutrients, as shown for BLG, is a novel approach exploiting targeted micronutrition to halt the allergy epidemic.