[Abnormal DNA methylation in CD4⁺ T cells from patients with immune related pancytopenia: a preliminary study]

To explore the global DNA methylation and the expression of regulatory genes for methylation in CD4⁺ T cells of the patients with immune related pancytopenia (IRP) and explore the role of methylation in the pathogenesis of IRP.

Thirty IRP patients (untreated, n = 15; remission, n = 15) and 15 healthy donors as controls were enrolled from December 2012 to December 2013. CD4⁺ T cells were sorted by immunomagnetic separation. The global DNA methylation was tested with enzyme-linked immunosorbent assay (ELISA). The mRNA levels of DNA methylation-related regulating genes, DNA methyltransferases (DNMTs) and methylated CpG binding proteins (MBDs), were measured by real-time quantitative-polymerase chain reaction (RT-PCR).

The level of global DNA methylation in peripheral blood CD4⁺ T cells of untreated IRP patients (3.525% ± 2.046%) and remission patients (4.790% ± 1.471%) were significantly lower than that of normal controls (10.101% ± 3.449%) respectively (both P < 0.05). DNMT3b mRNA level of untreated IRP patients (1.332 ± 0.785) was significantly lower than that of normal controls (2.077 ± 1.059) in CD4⁺ T cells (P < 0.05). The mRNA expression of MBD2 was significantly higher in CD4⁺ T cells from untreated and remission IRP patients (2.999 ± 1.601, 2.055 ± 1.576) than that in controls (0.581 ± 0.247) (both P < 0.05). The MBD4 mRNA level was significantly higher in CD4⁺ T cells from untreated IRP patients (2.736 ± 2.719) compared to that in normal controls (1.167 ± 1.006) (P < 0.05). DNMT3b mRNA expression and CD4⁺ T cell DNA methylation to be positive correlated within IRP patients (r = 0.569, P < 0.01). The MBD2 mRNA expression was negatively correlated with CD4⁺ T cell DNA methylation and the ratio of Th1/Th2 (r = -0.763, P < 0.01; r = -0.652, P < 0.05) . The global methylation of CD4⁺ T cells negatively related to the ratio of CD5⁺ B cells (r = -0.439, P < 0.05).

The globe DNA hypomethylation and abnormal expression of DNA methylation-related enzymes in peripheral blood CD4⁺ T cells may be related with the pathogenesis of IRP.