Lipocalin allergens have been shown to evoke a Th2-deviated immune response, important for allergic sensitization, when applied in their apo-form (with an empty calyx devoid of ligands), whereas the holo-form seemed to exert immune-suppressive properties in vitro.

Retinol, (vitamin A), is an important micronutrient that affects eyesight, cell differentiation, immune system function, bone growth, and tumor suppression.

However, lipophilic ligands, present as substituents to the lipocalins, have the ability to enter the cell, where they can act as tumor protease inhibitors.

Allergies are hypersensitivity reactions of the immune system to specific substances called allergens (such as pollen, stings, drugs, or food) that, in most people, result in no symptoms.

[citation needed] Although lipocalins are a broad family of greatly varied proteins, their three-dimensional structure is a unifying characteristic.

Lipocalins have an eight-stranded, antiparallel, symmetrical β-barrel fold, which is, in essence, a beta sheet which has been rolled into a cylindrical shape.

Inside this barrel is located a ligand binding site, which plays an important role in the lipocalin classification as a transport protein.