Prognostic significance of circulating CD19+ B lymphocytes in EBV-associated nasopharyngeal carcinoma

In this retrospective study, the correlation between pre- and post-treatment plasma Epstein–Barr virus (EBV) DNA and circulating immune subsets as well as the prognostic implications was investigated in nasopharyngeal carcinoma (NPC) patients. Patients (n = 356) were diagnosed and received comprehensive treatment at the First People’s Hospital of Foshan from 2006 to 2010. Pre- and post-treatment plasma EBV DNA load and circulating immune subsets (percentage of CD3+ T cell, CD3+ CD4+ T cells, CD3+ CD8+ T cells, CD19+ B cells and CD56+ NK cells) were analyzed by real-time PCR and flow cytometry. Patient age correlated negatively with CD3+ T cells (r = −0.264, P = 0.001) and positively with CD56+ NK cells (r = 0.272, P = 0.001). Pre-treatment plasma EBV DNA correlated negatively with CD19+ B cells (r = −0.223, P = 0.009) and CD4/CD8 ratio (r = −0.177, P = 0.047). Patients with low CD19+ B cell had poorer 5-year progression-free survival (PFS) (66.6 vs. 81.8 %, P = 0.036) and 5-year overall survival (OS) (70.5 vs. 81.5 %, P = 0.097) than patients with high CD19+ B cells. Low CD19+ B cells was identified as a negative prognostic factor for 5-year PFS (hazard ratio [HR] 0.487; P = 0.040), but not for 5-year OS (HR 0.550; P = 0.102) in multivariate analysis. Post-treatment plasma EBV DNA was the most important prognostic factor for 5-year PFS (HR 2.983; P = 0.006) and 5-year OS (HR 3.927; P < 0.001). This study demonstrates the clinical value of circulating CD19+ B cell measurements in NPC patients.