CD45R antibodies target isoforms of the CD45 glycoprotein, a transmembrane tyrosine phosphatase critical for immune cell signaling. CD45. also known as leukocyte common antigen (LCA), is ubiquitously expressed on all nucleated hematopoietic cells. Its extracellular domain contains variable exons (A, B, and C) that undergo alternative splicing, generating isoforms (e.g., CD45RA, CD45RB, CD45RC) with distinct molecular weights. These isoforms regulate T-cell receptor (TCR) and B-cell receptor (BCR) signaling by modulating phosphatase activity, thus influencing lymphocyte activation, differentiation, and tolerance.
CD45R antibodies specifically recognize epitopes encoded by these variable exons. For example, anti-CD45RA antibodies bind the A exon-encoded region, while anti-CD45RO targets the truncated isoform lacking variable exons. This specificity enables functional discrimination of lymphocyte subsets: CD45RA+ marks naïve T cells, whereas CD45RO+ identifies antigen-experienced memory T cells. Such distinctions are vital in immunophenotyping, particularly in studying immune aging, autoimmune diseases, and immunodeficiency disorders.
Clinically, CD45R antibodies are essential tools in flow cytometry for leukemia/lymphoma classification, as CD45 expression patterns differ between malignant cell types. Research applications include tracking immune reconstitution post-transplant and analyzing T-cell memory dynamics in infections or vaccines. However, interpretation requires caution, as isoform expression can vary with activation states and cell types. Despite these complexities, CD45R antibodies remain indispensable for dissecting immune cell heterogeneity and function.