About InVivoMAb anti-rat pan-CD45 (OX1) OX-1 is a pan-CD45 antibody that reacts with a common epitope present on all isotypes of rat CD45. The CD45 protein is also called leukocyte common antigen (LCA), RT7, T200, and protein tyrosine phosphatase, receptor type C (Ptprc). CD45 is a highly glycosylated protein with a molecular weight ranging from 142 to 220 kDa. CD45 is largely expressed in the lymphoid system, but it is also found in all hematopoietic cells except erythrocytes and platelets. Thymocytes and lymph nodes express CD45 isoforms 1 and 2, whereas other tissues express CD45 isoforms to varying levels depending on cell type and maturity or activation status. Functionally, CD45 is a protein tyrosine-protein phosphatase (PTPase), and its activity is enhanced by CD45-CD53 interaction. CD45 also binds to SKAP1, DPP4, GANAB, PRKCSH, and CLEC10A. CD45 interacts with DPP4 in activated lymphocytes in an interleukin-12-dependent manner, and it positively regulates T-cell coactivation. CD45 operates as a "signaling gatekeeper" by altering immune cell activation thresholds via its PTPase activity. Cancer cells use this phenomenon to avoid the immune system in the tumor microenvironment, and knowing the mechanisms offers opportunities for cancer immunotherapy. InVivoMAb anti-rat pan-CD45 (OX1) Specifications IsotypeMouse IgG1, κ Recommended Isotype Control(s)InVivoMAb mouse IgG1 isotype control, unknown specificity Recommended Dilution BufferInVivoPure pH 7.0 Dilution Buffer ImmunogenRat thymocyte membrane glycoproteins Reported Applicationsin vivo functional assay in vitro functional assay Immunohistochemistry (frozen) Immunohistochemistry (paraffin) Flow cytometry Immunofluorescence Immunoprecipitation FormulationPBS, pH 7.0 Contains no stabilizers or preservatives Endotoxin≤1EU/mg (≤0.001EU/μg)Determined by LAL gel clotting assay Purity≥95% Determined by SDS-PAGE Sterility0.2 μm filtered ProductionPurified from cell culture supernatant in an animal-free facility PurificationProtein G Molecular Weight150 kDa StorageThe antibody solution should be stored at the stock concentration at 4°C. Do not freeze. Application ReferencesInVivoMAb anti-rat pan-CD45 (OX1) (CLONE: OX-1)Takazoe K, Tesch GH, Hill PA, Hurst LA, Jun Z, Lan HY, Atkins RC, Nikolic-Paterson DJ (2000). "CD44-mediated neutrophil apoptosis in the rat" Kidney Int 58(5):1920-30. PubMedBackground: Apoptosis is an important mechanism by which neutrophils are removed from sites of inflammation, including the kidney. This study investigated whether ligation of the cell-surface adhesion molecule, CD44, can trigger neutrophil apoptosis. Methods: The anti-rat CD44 antibody OX-50 was used to induce apoptosis of cultured blood neutrophils, as determined by flow cytometry using annexin V staining and by transmission electron microscopy. The functional consequences of OX-50-mediated neutrophil depletion were examined in a rat model of accelerated antiglomerular basement membrane glomerulonephritis. Results: Flow cytometric analysis using the OX-50 antibody, which recognizes the common amino terminal domain of CD44, showed that rat blood neutrophils express very high levels of CD44. The addition of OX-50, but not control antibodies, rapidly induced neutrophil apoptosis in cultured rat blood leukocytes, as demonstrated by annexin V staining and by electron microscopy. Cross-linking of CD44 was essential since F(ab) fragments of the OX-50 antibody failed to induce neutrophil apoptosis. The CD44 ligand hyaluronan and an antibody to the CD44v6 isoform failed to induce neutrophil apoptosis, indicating that OX-50 antibody-mediated neutrophil apoptosis is epitope specific. This effect was specific to neutrophils since the OX-50 antibody did not induce apoptosis in other CD44-expressing cell types (lymphocytes, mesangial cells, or tubular epithelial cells). An injection of OX-50 antibody into normal rats caused a rapid and profound neutropenia, and apoptotic neutrophils could be seen in the blood by electron microscopy. Furthermore, the administration of OX-50 antibody abrogated neutrophil-dependent glomerular injury (proteinuria) on day 1 of rat antiglomerular basement membrane glomerulonephritis, whereas injury on day 10 of the disease (neutrophil independent) was largely unaffected. Conclusions: The cross-linking of specific epitopes of the CD44 molecule can rapidly induce neutrophil apoptosis in vitro and inhibit neutrophil-dependent renal injury in vivo. This finding suggests that physiological ligands of the CD44 molecule may play an important role in eliminating neutrophils from sites of inflammation, including inflammatory kidney disease.
