D2.420 - Sensitization Profile of Lipocalins: sIgE Analysis in a Large Cohort of Patients with Suspected Allergies

Lipocalins are one of the most commonly sensitizing groups of animal proteins. Nowadays, it is possible to examine sIgE to 15 different lipocalins using multiplex tests. This raises the question of whether the allergen profile of lipocalins may differ for various populations. The study examined this profile among Polish patients with suspected allergies.

The analysis included sIgE results for lipocalins (Arg r 1, Bla g 4, Bos d 2, Bos d 5, Can f 1, Can f 2, Can f 4, Can f 6, Cav p 1, Equ c 1, Fel d 4, Fel d 7, Mus m 1, Ory c 1, Phod s 1) based on results from the ALEX test of 17 821 Polish patients (9121 females and 8700 males) suspected of allergy. The median age was 21,8 years. sIgE ≥ 0.3 kU/L was considered positive. The study was approved by the Bioethics Committee. Statistical analysis used SPSS. 

In the study group, more than ⅕ were sensitized to any lipocalins tested. The most frequently sensitizing lipocalins were Can f 1 - 11.5%, Fel d 7 - 8.1%, and Can f 4 - 6.2%. The least sensitizing were Bos d 2 (0.6%) and Arg r 1 (0.5%).

Can f 1 sensitized 13.3% of men and 9.8% of women, Fel d 7 sensitized 8.9% of men and 7.4% of women. A statistically significant difference was observed between men and women for 6 (Bos d 2, Bos d 5, Can f 1, Can f 2, Can f 4, Fel d 7) of the 15 lipocalins (p<0.05). The highest sIgE concentration was found for the following allergens Can f 4 (15.2 kU/L), Can f 2 (12.4), Can f 6 (11.9). Women obtained the highest sIgE concentration for Can f 4 (15.9), Can f 2 (13.4), Can f 6 (12.0), and men for  Can f 4 (14.5), Mus m 1 (12.3), and Can f 6 (11.8).

In children, positive results were most often found for Can f 1 (15%), Fel d 7 (10%), Can f 4 (8%), Can f 6 (8%). In adults, the most common positive result was found for: Can f 1 (8%), Fel d 7 (6%). All lipocalins showed different positive result frequencies between children and adults (p < 0.05), with sIgE positivity more common in children in all significant cases.

The most common case when an individual was positive to at least one lipocalin, was sensitization to 1 molecule (37.8%), followed by 2 (20.5%) and 3 (13.5%). When considering patients who were positive to any of the lipocalins, the most common sensitization was to a single Can f 1 (9.5%), followed by Bos d 5 (7.9%), or to combinations of Can f 1 and Fel d 7 (7.7%). 

The most frequently sensitizing lipocalins were derived from dogs and cats. Men were more commonly sensitized to lipocalins, while women had results with higher sIgE concentrations. Additionally, polysensitization to lipocalins occurred more frequently than monosensitization, indicating the high level of cross-reactivity between lipocalins.