Pediatric brain tumor patients display altered immune activation and reduced lymphopoiesis at the onset of disease.

Optimal immune function is crucial in preventing cancer development and growth and for the success of anti-cancer therapies. Here, we characterized the peripheral immunological status of 83 steroids-naïve pediatric patients with central nervous system neoplasia at the disease onset. Tumors were classified into low-grade gliomas (LGG), high-grade gliomas (HGG), medulloblastoma, and other tumors. We revealed that glioma patients showed an altered lymphocyte pool. T-cells of HGG patients shifted from naïve to effector memory phenotype. LGG patients exhibited T-cell central memory expansion and higher T-cell activation. Interestingly, HGG patients displayed reduced thymic function. Furthermore, LGG and HGG patients showed reduced activated B-cells and suboptimal B-cell formation. Our data demonstrate that glioma patients have reduced lymphopoiesis at the disease onset, which could contribute to the systemic lymphopenia characterizing these patients. This study offers novel insights into the immunological status of brain tumor patients which may help in designing more effective treatments.