Changes in Differential Gene and Protein Expression Patterns during Development of Cord Blood (CB) Versus Adult Peripheral Blood (APB) Monocyte (Mo) into Mature Dendritic Cells (mDC): Insight into Immaturity of CB DC Immunity.

It has been recognized that dysfunction of CB immune system is in part due to the immaturity of CB cellular immunity (Cairo, Blood,1997). The molecular mechanisms associated with the immaturity of CB cellular immunity including DC subset remain to be defined. The maturation status of DC greatly influences its antigen presentation capacity. Recently, we have utilized oligonucleotide microarray to demonstrate differential gene expression profiles of CB vs APB Mo (Jiang/Cairo, JI, 2004). In the current study, differential expressed genes and proteins were examined in Mo-derived CB vs. APB DC during DC developmental stages: Mo, immature DC (iDC) and mDC, by utilizing oligonucleotide microarray and proteomics. Briefly, Mo isolated from CB or APB and cultured for 8 days with GM-CSF/IL-4 (iDC) and further stimulated with LPS (mDC). Oligonucleotide microarray was carried out using U133A gene chip (Affymetrix). The representative differentially expressed genes resulted from microarray analysis were selected and analyzed by quantitative RT-PCR (Roche). The proteomic technique was conducted by liquid chromatography (LC) and mass spectrometry (MS) (Lim, Mol Cell Proteomics, 2006). The differentially expressed proteins were compared in CB vs. APB for iDC and mDC. We identified different gene expression patterns that were significantly lower in CB vs. APB in different stages during DC differentiation: Mo, iDC and mDC. These differentially expressed genes included RELA (5F), JUNB (6F), IRF-1 (3F) in Mo; CREB5 (3F), MAP7 (5F), IL1R2 (6F) in iDC; and HLA-DQA1 (4F), CD80 (3F), IRF-5 (3F) in mDC. The proteomic studies demonstrated Tyrosine Kinase Fer (12.5F), Actin regulator 3 (2.5F), Rap guanine nucleotide exchange factor 1 (2.4F) and Myeloid cell nuclear differentiation antigen (1.5F) were expressed higher in APB vs.CB iDC, while MAX binding protein MNT (5.5F), IRS2 (2.2F) and Zinc-Finger Proteins (514, 212, 462) (3–14F) were expressed higher in CB vs. APB iDC. Further, the proteomic results also indicated other Zinc-Finger Proteins (292, 221, 474) (2–5F), Fibrillin 1 precursor (2.5F) and interleukin-4 (7.7F) were expressed higher in APB vs. CB mDC. In contrast, cyclin I (3F), Rb-like protein 2 (4.35 F) and PKC theta (2F) were significantly lower in APB vs. CB DC. Moreover, the comparison of CB vs. APB DC antigen presenting activity by ELISPOT was performed and the influenza-peptide loaded CB-mDC demonstrated weaker ability to induce T cells to produce IFNg compared with APB-mDC. In summary, these differentially expressed genes in Mo (RELA, JUN) may play key roles in initiating Mo differentiation toward DC. The increased expression of genes in APB vs. CB iDC, like CREB5, IL1R2, may be involved in mediating maturation process of iDC to mDC. Lastly, the elevated expression of genes in APB vs. CB mDC, such as HLA-DQA1, CD80, IRF5 among others, may be likely to control mDC functionality as demonstrated by weaker antigen presenting activity of CB vs. APB mDC. We postulate that decreased expression of specific genes in CB vs. APB DC during DC developmental stages may in part be responsible for the lack of maturity of CB, and ultimately may partially be responsible for differential CB vs. APB innate and adaptive immunity.