Expression of Leucine-rich Repeat-containing Protein 32 Following Lymphocyte Stimulation in Patients with Non-IgE-mediated Gastrointestinal Food Allergies

The lymphocyte stimulation test (LST) facilitates the diagnosis of non-IgE-mediated gastrointestinal food allergies (non-IgE-GI-FAs). However, LSTs require large volumes of blood and prolonged culture durations. Recently, we found that mRNA expression in peripheral blood mononuclear cells (PBMCs) of patients with non-IgE-GI-FAs increased after a 24 h stimulation with milk proteins. We designated this gene expression test as the instant peripheral blood allergen stimulation test (iPAST). In this study, we investigated whether other activated T cell-associated genes are superior to in the iPAST for the supplementary diagnosis of non-IgE-GI-FAs. After incubating PBMCs with milk proteins for 24 h, the mRNA levels of three genes, , , and , were assessed using quantitative RT-PCR. The diagnostic significance of the mRNA expression was evaluated by analyzing the receiver operating characteristic (ROC) curve. Upon stimulation with α-casein, κ-casein, α-lactalbumin, or a mixture of four milk protein components (Pmix), expression in the PBMCs of 16 patients with non-IgE-GI-FAs was found to be higher than that in their 17 control counterparts, whereas and levels remained unaltered. Except for β-lactoglobulin and cow's milk (CM), the area under the ROC curve (AUC) for mRNA expression upon stimulation was >0.7, which validated the diagnostic ability of this test. Notably, α-casein and Pmix had higher AUC scores of 0.820 and 0.842, respectively, than other antigens. iPAST assessed by as well as may be useful for the supplementary diagnosis of non-IgE-GI-FAs as an alternative to LSTs and provide insight into the pathogenesis of non-IgE-GI-FAs.