Cryopreserved Human Peripheral Blood Mononuclear Cells are available as positive and negative controls for T-cell monitoring in ELISPOT, ELISA, cytokine bead array, tetramer/pentamer, and flow cytometry assays. A peripheral blood mononuclear cell is defined as any blood cell with a round nucleus. These blood cells are a critical component in the immune system to fight infection and adapt to intruders. The lymphocyte population consists of CD4 and CD8 T cells, B cells and Natural Killer cells,