Peripheral blood CD4+CD45RO+ memory T cells are formed after a naïve T cell has come into contact with an antigen. Memory T cells remain inactive until they encounter the same antigen and reactivate to form effector T cells. Having encountered the antigen previously this second encounter produces a faster and stronger immune response to eliminate the foreign invader or cancer cell.

Human CD4+CD45RO+ memory T cells are isolated from peripheral blood mononuclear cells by depleting cells expressing CD8, CD14, CD16, CD19, CD20, CD36, CD45RA, CD56, CD123, TCRγ/δ, and CD235a using immunomagnetic particles leaving purified, untouched CD4+CD45RO+ memory T cells. Isolated cells are characterized by flow cytometry before cryopreservation to ensure a highly pure and viable cell population.

Cells were obtained using Institutional Review Board (IRB) approved consent forms and protocols.