Background: Immunoglobulin E (IgE) drives type 2 inflammation in allergic asthma, whereas interleukin-37 (IL-37) has been proposed as an endogenous restraint on airway inflammation.
Objectives: To quantify serum total IgE, allergen-specific IgE and IL-37 in adults with asthma and relate them to haematological indices.
Methods: In this hospital-based case–control study conducted in Baghdad from November 2025 to March 2026, 60 adults with physician-diagnosed asthma and 40 self-reported healthy, non-atopic controls were enrolled by consecutive sampling. Total IgE and IL-37 were measured by enzyme-linked immunosorbent assay.
Results: Total IgE and IL-37 were non-normally distributed and are therefore reported as medians with interquartile ranges (IQRs). Both were higher in patients with asthma than in controls: total IgE, 351.80 (200.20–546.90) versus 68.23 (48.22–82.52) IU/mL (P < 0.0001), and IL-37, 127.20 (101.50–173.30) versus 67.36 (45.36–80.15) pg/mL (P < 0.0001). Eosinophil and basophil percentages were higher and monocyte percentage was lower after Bonferroni correction. Total IgE showed nominal positive monotonic correlations with monocytes (rₛ = 0.384, P = 0.003) and lymphocytes (rₛ = 0.333, P = 0.010), and nominal inverse correlations with eosinophils (rₛ = −0.329, P = 0.011), neutrophils (rₛ = −0.326, P = 0.012) and basophils (rₛ = −0.281, P = 0.031). None of these IgE correlations remained significant after Bonferroni correction for 55 correlations (adjusted threshold P < 0.0009).
Conclusions: Adults with asthma in Baghdad had higher total IgE, IL-37, eosinophil percentage and basophil percentage than the selected controls, together with a locally distinctive aeroallergen-sensitisation pattern. The IL-37 elevation may be consistent