Protein tyrosine phosphatase receptor type C (CD45) (CD45)

Protein tyrosine phosphatase receptor type C (CD45) is a heavily glycosylated transmembrane protein expressed on the surface of all nucleated hematopoietic cells and their precursors. It functions as a critical regulator of T-cell and B-cell antigen receptor signaling by dephosphorylating inhibitory sites on Src family kinases, such as Lck and Fyn [UniProt]. Due to its high expression across the hematopoietic lineage, it serves as a cornerstone biomarker in clinical flow cytometry for the diagnosis and classification of leukemias and lymphomas [StatPearls]. In therapeutic contexts, CD45 is primarily targeted via radioimmunotherapy, such as the antibody apamistamab, which is used to condition patients for bone marrow transplants by depleting host immune and cancer cells [Actinium Pharmaceuticals]. Genetic deficiencies in CD45 lead to severe combined immunodeficiency (SCID) in humans, highlighting its essential role in lymphocyte development and functional immunity [PubMed]. While the phosphatase activity itself is a theoretical target for autoimmune disorders, most clinical-stage therapies leverage CD45 as a cell-surface anchor for the delivery of cytotoxic payloads [Nature Reviews Drug Discovery].

Other names

PTPRCLeukocyte common antigenLCAT200Ly-5B220GP180

Radioimmunotherapy (targeted delivery of radioisotopes for hematopoietic cell depletion), antibody-mediated cell depletion, and inhibition of phosphatase catalytic activity to modulate immune signaling.