Clinical relevance of Alternaria alternata sensitization in patients within type 2-high and type 2-low asthma

Alternaria sensitization is correlated with persistent asthma. Type 2 (T2)-asthma endotypes are characterized by the release of eosinophils. However, the prevalence and sensitization patterns in patients with Alternaria asthma between T2-high and T2-low endotypes are unknown. We retrospectively reviewed 582 patients with Alternaria asthma and divided them into T2-high (n = 376) and T2-low (n = 206) groups with a threshold of 300 cells/µL in blood eosinophil counts. Data for basic information, skin test or IgE detection results, and blood eosinophil counts were collected. The age of patients in the T2-high group (13.66 ± 13.23) was lower than that of the T2-low group (18.02 ± 15.03). Patients with T2-high asthma had relatively higher rates of taking inhaled corticosteroids (ICS) and positive family history than the T2-low group. Pet keepers and allergen immunotherapy (AIT) patients were comparable between these groups, In the T2-high group, patients had higher levels of total serum IgE (T-IgE) and showed a significant positive correlation with eosinophil counts (r = 0.166, P = 0.001), followed by higher Alternaria-specific IgE (sIgE) levels (median, 13.7; range, 4.86-25.3). Compared to the T2-low group, the frequency of poly-sensitized patients and the rate of each allergen among the nine common allergens were all higher in the T2-high group; the statistical differences mainly focused on pollens such as birch (P = 0.005), firmiana (P = 0.004), and mugwort (P = 0.005). Young, male patients had a high prevalence of T2-high Alternaria asthma, along with higher rates of T-IgE, sIgE levels, and poly-sensitized patterns.