Identification of immunodeficient molecules in neonatal mononuclear cells by proteomic differential displays

Human newborns are known to be susceptible to microbial infection. This susceptibility is generally attributed to immaturity of the newborn immune system. However, the mechanisms for impaired immunity in newborns are still incompletely defined. In this study, we sought to elucidate the protein differential display between adult and neonatal mononuclear cells (MNC) using a proteomic approach. MNC samples from cord blood and adult peripheral blood were subjected to 2-D PAGE analysis. Differential protein displays between cord blood and adult MNC were determined and validated. There were 34 differentially expressed proteins between cord blood and adult MNC identified by 2-D PAGE. The differentially displayed proteins were clustered into two major signal pathways, cellular processing and purine metabolism. After validation by Western blot, we found more abundant arginase-1 (ARG1) and Rho GDP-dissociation inhibitor 2 (RhoGDI2), while less adenosine deaminase (ADA) and β-actin in cord blood MNC. In functional validation, we found that lower ADA was proven to enhance the TNF-α production by cord blood monocytes. The results from this study discovered the proteomic displays for altered immunity between adult and neonatal MNC that support a understanding of the correction of impaired immune response in newborns.