Association between the type of allergen and T-helper 2 mediated inflammation in allergic reactions: a systematic review and a meta-analysis

Abstract

Objectives: To determine whether the levels of T-helper (TH) 2 cytokines (interleukin (IL)-4 and IL-5) in allergic reactions are allergen dependent and evaluate the impact of various treatment strategies on the levels of these cytokines.Methods: The PubMed search engine was used from inception until January 2021. The random-effects residual maximum likelihood model was performed, and effect sizes were estimated using the Hedge’s g statistic. All data analysis was performed using STATA 16.0 (StataCorp LP, TX, USA). Results: Fourteen studies reporting on 794 participants were included in this study. House dust mite was associated with eliciting a stronger immune response mediated by both IL-4 and IL-5 when compared to pollen. Whereas a mixture of house dust mite and pollen was associated with IL-4-weighted inflammation. Comparisons of IL-4 and IL-5 levels amongst the allergens showed significant differences. The treatment with anti-corticosteroids or allergen-specific immunotherapy was effective in normalising the TH2 responses and alleviating allergy symptoms.Conclusion: TH2-mediated inflammation in allergic reactions is allergen-dependent. Therefore, the type of allergen should be considered when using cytokine-targeting biologics in allergic reactions.