IMMU-49. DYNAMIC CHANGES AND PROGNOSTIC VALUE OF PERIPHERAL BLOOD LYMPHOCYTE SUBSETS IN INTRACRANIAL GERM CELL TUMORS

Abstract OBJECTIVE This study was designed to retrospectively analyze the dynamic changes of peripheral blood lymphocyte subsets and prognosis among patients with intracranial germ cell tumors. METHODS A total of 150 intracranial germ cell tumors patients diagnosed between June 2011 till November 2019 were retrospectively investigated. Peripheral blood total T lymphocytes (CD3+) percentage, T helper/inducible lymphocytes(CD3+CD4+)percentage, T inhibitory/toxic lymphocytes (CD3+CD8+) percentage, B lymphocyte (CD19+) percentage, NK lymphocyte (CD3/CD16+CD56+) percentage, regulatory T cells (CD4+CD25+,CD8+CD25+), and T helper/toxic lymphocyte ratio (CD4+/CD8+ ratio) were quantified by flow cytometry analysis. Clinical information was extracted from the database in Sun Yat-sen University Cancer Center and survival data was confirmed through outpatient visits and telephone follow-up. RESULTS T lymphocytes population was increased after anti-tumor treatment, with significant difference of total T lymphocytes (CD3+), inhibitory/toxic T cells (CD3+CD8+) and regulatory T cells (CD4+CD25+ and CD8+CD25+), (p=0.008, p=0.000, p=0.008 and p=0.001 respectively), while B lymphocytes(CD19+) decreased after chemotherapy(p=0.003). The dynamic levels of T lymphocyte and B lymphocyte subpopulation after chemotherapy did not present significant differences between gender, age, and locations of tumors (p >0.05), except CD4+CD25+ T cells in younger children (age< 16 years older) increased significantly than the elder (age >16), p=0.04. Patients with increased CD19+ B cells presented significant suboptimal outcomes compared with the no increased (p=0.024). Similarly, increased CD3+ T cells, CD3+CD8+ T cells, CD4+CD25+ T cells reduced the risk of death (p=0.006, p=0.019, p=0.042 respectively). Multivariate Cox Regression analysis showed: increased CD19+ B cells, p=0.04, HR=1.688, 95%CI=1.025-2.779. CONCLUSION After anti-tumor treatment, cell-mediated immunity activated, enhanced, and dominated in anti-tumor response. An increased level of CD19+ subsets was an independent predictor for inferior overall survival. Systemic circulating T cells immunity played an important role and mediating antitumor responses may pave the road for new immunity strategies.