Serum IgE profiles in Chinese pollinosis patients with grass pollen sensitisation

Pollen from trees, grasses, and weeds is a common allergen source. The characteristics of pollen allergy in China are obviously different from Europe. Most studies have focused on tree and weed pollen, but there is a paucity of data on grass pollen sensitisation in China. Therefore, we used component-resolved diagnostics to investigate the serum-specific immunoglobulin E (sIgE) to grass pollen in Chinese patients with pollinosis.

We retrospectively analysed 547 patients with pollen allegy from an outpatient Allergy Department in Beijing, China. All the patients answered questionnaires about their clinical allergy histories. Total immunoglobulin E (IgE) and sIgE levels to grass pollen (Bermuda, Timothy grass) were quantified by ImmunoCAP using 0.35 kUA/L as a threshold for positivity.

Of the 547 pollinosis patients, 389 (71.1%) showed a positive sIgE reaction to either grass pollen, or both. The prevalence of food allergy was significantly lower in patients with grass pollen sensitisation. Among the 389 patients with grass pollen sensitisation, the prevalence of sIgE to allergen extracts of bermuda, mugwort, ragweed, plane, hop, ash, birch, and timothy grass was 97%, 96%, 94%, 88%, 88%, 84%, 78%, and 78%, respectively. However, only 134/389 (34%) were positive for Cyn d 1, 29/389 (7%) for Phl p 1, and 8/389 (2%) for Phl p 5b. For pollinosis patients, 62/547 (11%) were sIgE-positive for cross-reactive carbohydrate determinants (CCDs), and their grass pollen-sIgE was also positive.

The prevalence of in vitro IgE sensitisation to grass pollen extract is high in Chinese patients with pollinosis. But mostly spurious and characterized by IgE sensitisation to profilins and CCD, induced by other pollen. Component-resolved diagnostics is an extremely useful tool precise diagnostics of pollen allergy in China.