The biology of CD45 and its use as a therapeutic target.

All mature hemopoietic lineage cells, with exclusion of platelets and mature erythrocytes, share the surface expression of a transmembrane phosphatase, the CD45 molecule. It is also present on hemopoietic stem cells and most leukemic clones and therefore presents as an appropriate target for immunotherapy with anti-CD45 antibodies. This short review details the biology of CD45 and its recent targeting for both treatment of malignant disorders and tolerance induction. In particular, the question of potential stem cell depletion for induction of central tolerance or depletion of malignant hemopoietic cells is addressed. Mechanisms underlying the effects downstream of CD45 binding to the cell surface are discussed.