Cord blood eosinophil progenitor expression of major basic protein mRNA is associated with maternal atopic sensitization

RATIONALE: We recently developed and validated multiplex Q-PCR analyses of key eosinophil-lineage gene_including that of major basic protein-1(MBP1)_in cord blood(CB) progenitor populations stimulated with IL-5. Our current objective was to determine if differences exist in kinetic expression patterns of MBP1 mRNA by Q-PCR in IL-5 stimulated CB non-adherent mononuclear cells(NAMNC) between infants born to atopic(>1 positive skin prick tests(SPTs) vs. non-atopic(negative SPTs) mothers. METHODS: CB NAMNC were isolated from 10 atopic and 10 non-atopic mothers participating in a prospective birth cohort study. Cells were incubated with 1 ng/mL rhIL-5; at 24, 48 and 72h post-stimulation, RNA was isolated, reverse transcribed, and expression of MBP mRNA determined, utilizing multiplex Q-PCR with GAPDH and beta-actin as housekeeping genes. Relative expression ratios of stimulated and un-stimulated cells were calculated using the ΔΔCt method. RESULTS: Stimulation of CB NAMNC with IL-5 resulted steady up-regulation of MBP1, as previously demonstrated in random CB donors. Differences were noted in MBP1 mRNA expression levels between infants born to atopic vs. non-atopic mothers: the mean fold increase at 48h was 1.7 for non-atopics, vs. 8.1 for atopics(p=0.032), and at 72h 9.9 for the non-atopics vs. 18.2 for the atopics(p = 0.046) on independent samples t-testing. CONCLUSION: Multiplex Q-PCR analyses of MBP1 mRNA from CB eosinophil progenitors demonstrate enhanced sequential expression of critical eosinophil lineage-specific genes, in subjects born to atopic vs. non-atopic mothers. These findings suggest upregulation of eosinophilopoiesis as a result of maternal allergen sensitisation, and could be applied to provide CB molecular biomarkers of the atopic diathesis.