The method of data presentation and sample preparation can affect immune phenotype results. A. T cells, B cells, and lymphocytes were reported as a fraction of a larger population (top graphs) or enumerated by cell counts (cells/μl) (bottom graphs) from glioblastoma patients (n = 27) and healthy volunteer controls (n = 40). B. NK cells reported as a percentage of lymphocytes or NK cells and lymphocytes reported per unit of blood for GBM patients at baseline (n = 13), treatment (n = 12) and compared to HV controls C. Measuring leukocytes per unit of blood allows complete reconstitution of the composition of blood. Pie graphs representing the mononuclear compartment of healthy volunteers (HV) and glioblastoma patients (GBM) includes CD4+CD3+ T cells (dark blue), CD8+CD3+ T cells (light blue), regulatory T cells (CD25+CD127loCD4+CD3+, white), CD19+ B cells (green), CD56+CD16+ NK cells (yellow), CD14+HLA-DR+ monocytes (black), and CD14+HLA-DRlo/neg monocytes (red). D. CD14 and CD16 bivariate plot overlay of CD14+ gated monocytes from cells stained from whole blood (black) and the same sample with cells stained from density gradient centrifugation (PBMC; red). Comparison of classical (CD14+CD16−) and intermediate monocyte (CD14+CD16+) populations from ten healthy volunteer blood samples that were either directly stained from whole blood or stained from PBMCs. All studies were performed under the review and approval of the Mayo Clinic Institutional Review Board. Asterisk indicates p < 0.05 and ** indicates p < 0.005 by Mann–Whitney test for unpaired samples.