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

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.

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

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.

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).

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.