Better detection of Ig heavy chain and TCRγ gene rearrangement in plasma cell-free DNA from patients with non-Hodgkin Lymphoma

Plasma cell-free DNA is the soluble DNA and tumor-derived DNA in plasma which has the same mutation as the tumor cellular DNA. This study aimed at comparing the properties of plasma cell-free DNA with the biopsy's DNA in order to evaluate the clinical significance of IgH and TCR gamma gene rearrangement in plasma cell-free DNA from patients with non-Hodgkin's Lymphoma. A total of 360 samples were studied. IgH (FR3A/VLJH) and TCR gamma (TVG/TJX) were amplified by PCR. Results of plasma cell-free DNA were compared with biopsy's DNA and mononuclear cellular DNA respectively. Plasma cell-free DNA were successfully extracted from 288 cases of newly diagnosed, refractory and relapsed NHL in total 360 patients (80%),But nothing was found in the other 72 remittent patients. The positive percentage of IgH rearrangement in patients with B-NHL was 81% in plasma cell-free DNA and 77% in biopsy's DNA (P>0.05). As to the ratio of TCR gamma rearrangement in patients with T-NHL, the former was 44%, and the latter was 39% (P>0.05). These results show tumor-derived DNA could be detected in tumor loaded plasma, even of underlying cancer patients. For NHL patients, detecting IgH and TCR gamma gene rearrangement of plasma cell-free DNA has the same clinical significance as biopsy's DNA. Moreover, it's more simple, convenient and non-invasive.