Differences in gene expression and cytokine levels between newly diagnosed and chronic pediatric ITP.

Immune thrombocytopenia (ITP) is an autoimmune disease where platelets are destroyed prematurely. In the majority of children the disease resolves, but in some it becomes chronic. To investigate whether these 2 phases of the disease are molecularly similar or separate entities we performed DNA microarray analysis (GEO accession number: GSE46922) of T-cells from newly diagnosed children and children with chronic ITP. We found complete separation of the gene expression profiles between the 2 phases of the disease. Furthermore, the gene expression levels of several cytokines differed between the 2 phases of the disease. This was also reflected in plasma with increased levels of interleukin (IL)-16 and TNF-related weak inducer of apoptosis and lower levels of IL-4 in newly diagnosed compared with chronic ITP. Thus, our data indicate that chronic ITP in childhood is a separate disease entity, dissimilar in many aspects to the newly diagnosed phase.