CD4 and CD45RA, the highest molecular weight isoform of CD45,  are co-expressed on naive CD4+T cells.

A naïve T cell (Th0 cell) is a T cell that has differentiated in bone marrow, and successfully undergone the positive and negative processes of central selection in the thymus.  A naïve T cell is considered mature and, unlike activated or memory T cells, has not encountered its cognate antigen within the periphery.

Our Human Cord Blood CD4+/CD45RA+ naive T cells are isolated from cord blood mononuclear cells using immunomagnetic selection.  All cord blood is collected in Citric Phosphate with Dextrose Buffer (CPD) from fully consented IRB approved donors and protocol.

CD45 (CD stands for cluster of differentiation),originally called leukocyte common antigen (LCA),  is a protein tyrosine phosphatase regulating src-family kinases, expressing on all hematopoietic cells.  CD45 can be expressed as one of several isoforms by alternative splicing of exons that comprise the extracellular domain. CD45RA is expressed on naïve T cells, as well as the effector cells in both CD4 and CD8.  After antigen experience, central and effector memory T cells gain expression of CD45RO and lose expression of CD45RA.  Thus either CD45RA or CD45RO is used to generally differentiate the naïve from memory populations.