CD45 is a 180-220 kDa protein, also known as the Leukocyte Common Antigen (LCA). It is a protein tyrosine phosphatase that exists in multiple isoforms generated by alternative splicing of exons within the extracellular domain and differential glycosylation. CD45 is expressed on all hematopoietic cells except erythrocytes and platelets; the expression of specific isoforms depends on cell type, activation status, and maturation stage. It is essential for signal transduction through the T-cell and B-cell antigen receptors. CD45 has been shown to interact with various proteins, including galectin-1, CD2, CD3, and CD4. The OX-1 antibody has been demonstrated to partially inhibit NK cell-mediated lysis of syngeneic tumor cells in vitro.
