Non-Atopic Infants Have Distinct Plasma Cytokine Profiles Compared to Atopic Infants

Discrete cytokine profiles in infancy have shown to predict development of atopy but biomarkers of non-atopic infants have not been established. A cohort of 82 healthy, vaginally delivered, term newborns were evaluated at birth, 6 months, and 12 months and monitored for development of atopic conditions (eczema, food allergy, allergic rhinitis and/or asthma) until age 5. Plasma levels of APRIL, BAFF, IL-2, sCD40L, IL-1β, IL-4, IL-17, IL-21, IL-22, IL-25, IL-31, IL-33, IFN-ɣ, sCD163, and sCD14 were measured using multiplex/ELISA assays. Cytokine levels were compared between study groups using unpaired nonparametric t test. A post hoc power analysis was conducted to determine sample size needed to reach significance. Clinical outcomes were available from 39 participants (48% of total enrolled), of whom 20 (51%) had evidence of atopy and 19 (49%) did not. While there was no significant difference in any of the biomarkers between atopic and non-atopic infants, IL-25, IFNγ, IL-21, and sCD163 showed differences approaching significance at 6 months (p = 0.06 - 0.08). An exploratory power analysis indicated that approximately 30 participants in each group are needed to detect meaningful differences between two groups for IL-25 and IFNγ, with an effect size 0.68, alpha 0.1, and power 0.8. In contrast, IL-21, and sCD163 had larger distribution and smaller effect sizes requiring samples of 50 to 60 per group. Early biomarkers of immunity can assess risk for atopic conditions, even with small sample sizes. Infants without atopy need to be included as a comparison group to establish reference ranges.