The diagnosis of lipid transfer protein allergy—Discriminating between sensitisation and allergy

Background

Sensitisation to Lipid Transfer Proteins (LTP), usually ascertained by undertaking a test to the peach LTP allergen Pru p 3, is common but does not always indicate LTP allergy. Improving the diagnostic process would ensure the correct diagnosis and management of this complex condition.

Objectives

To determine the diagnostic value of Pru p 3 and other LTP component allergens in UK adults.

Methods

A retrospective review was undertaken of adults referred to the Allergy Unit at the Royal Brompton & Harefield Hospitals (RBHT) London (UK), between 2012 and 2022 who were sensitised to Pru p 3. Those with a final diagnosis of LTP allergy were compared to those sensitized to Pru p 3 but not diagnosed with LTP allergy.

Results

Of 285 patients with a positive Pru p 3, 157 (55%) were diagnosed with LTP allergy. LTP allergic patients were more likely to have a higher level of Pru p 3, and a lower level of total IgE. The ratio of Pru p 3:total IgE was the most accurate diagnostic marker of LTP allergy, with a receiver operating characteristics AUC of 0.880. A diagnosis of LTP allergy was also significantly associated with sensitisation to the LTP in peanut (Ara h 9, p < 0.001), and hazelnut (Cor a 8, p < 0.001).

Conclusion

Sensitisation to Pru p 3 may not always indicate an LTP allergy. Our data suggests that the Pru p 3:total IgE ratio, and sensitisation to Ara h 9 and Cor a 8 can support the diagnosis of LTP allergy in individuals sensitised to Pru p 3.