Reduced expression of gm-csf receptor on cord blood progenitor cells from neonates at risk for atopy

Recent evidence points to an association between allergic asthma and increased responsiveness of eosinophil progenitor cells to hematopoietic growth factors. However, it is not clear at what age this phenomenon first becomes manifest. Objective: Compare expression of cytokine receptors on CD34+ progenitor cells in cord blood from normal infants ('low risk') and infants with at least one atopic first degree relative ('at risk'). Methods: Cord blood was obtained from 21 neonates. Cells were stained with antibodies directed against CD45, CD34, and the a chains of the GM-CSF, IL-3 and IL-5 receptors, and analyzed by flow cytometry. Results: No differences in absolute CD34 numbers were observed between the two groups. Surprisingly, expression of GM-CSF receptor on CD34+ cells was reduced in the 'at risk' group (1.92±O.89%; ±se) compared to the 'low risk' group (5.62±1.30%; p<0.03), while no significant differences were noted between the two groups with respect to IL-3 and IL-5 receptor expression. Conclusion: Our results suggest an association between genetic risk for atopy and the level of GM-CSF receptor expression on hematopoietic progenitor cells at birth. The functional sequelae of this reduction, and any relationship this might have to the emergence of the atopic phenotype, remain to be determined.