Receptor-type tyrosine-protein phosphatase C (CD45) (CD45)

Receptor-type tyrosine-protein phosphatase C, commonly known as CD45, is a high-molecular-weight transmembrane glycoprotein expressed on the surface of all nucleated hematopoietic cells [1, 3]. It serves as a pivotal regulator of immune cell signaling by functioning as a protein tyrosine phosphatase that modulates the activity of Src family kinases, such as Lck and Fyn, which are essential for T-cell and B-cell receptor activation [1, 5, 6]. Additionally, CD45 negatively regulates cytokine signaling by dephosphorylating JAK kinases, thereby influencing hematopoiesis and inflammatory responses [3, 12]. Due to its ubiquitous expression on leukocytes and its role in cell proliferation, CD45 is a significant therapeutic target in hematological malignancies like leukemia and lymphoma, as well as in autoimmune diseases and organ transplantation [1, 2, 10]. Therapeutic strategies include the use of radioimmunotherapy (e.g., Iomab-B) and antibody-drug conjugates for targeted depletion of hematopoietic cells during bone marrow conditioning [13, 15]. Small molecule inhibitors are also being explored to modulate its phosphatase activity for the treatment of autoimmune conditions [2, 9]. However, targeting CD45 presents challenges such as potential pancytopenia and broad immunosuppression due to its widespread presence across the immune system [1, 13].

Other names

PTPRCLeukocyte common antigenLCAB220T200Ly-5GP180CD45R

CD45 functions as a protein tyrosine phosphatase that dephosphorylates Src family kinases to activate antigen receptor signaling and dephosphorylates JAK kinases to inhibit cytokine signaling; therapeutic drugs target CD45 for targeted cell depletion via radioimmunotherapy or antibody-drug conjugates, or for immune modulation via phosphatase inhibition.