CD45 tyrosine phosphatase inhibits erythroid differentiation of umbilical cord blood CD34+ cells associated with selective inactivation of Lyn

• Published in: Blood Vol. 100; no. 13; pp. 4440 - 4445
• Main Authors: Harashima, Akira, Suzuki, Motoyuki, Okochi, Ayumi, Yamamoto, Mayuko, Matsuo, Yoshinobu, Motoda, Ryuichi, Yoshioka, Tamotsu, Orita, Kunzo
• Format: Journal Article
• Language: English
• Published: Washington, DC Elsevier Inc 15.12.2002; The Americain Society of Hematology
• Subjects: Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Antibodies, Monoclonal - pharmacology; Applied cell therapy and gene therapy; Biological and medical sciences; Cell Differentiation - drug effects; Cell Division - drug effects; Coculture Techniques; Erythroid Precursor Cells - cytology; Erythroid Precursor Cells - drug effects; Erythropoiesis - drug effects; Erythropoietin - antagonists & inhibitors; Erythropoietin - pharmacology; Fetal Blood - cytology; Hematopoietic Stem Cells - cytology; Hematopoietic Stem Cells - drug effects; Humans; Interleukin-3 - pharmacology; Janus Kinase 2; Leukocyte Common Antigens - immunology; Leukocyte Common Antigens - physiology; Medical sciences; Mice; Phosphorylation; Protein Processing, Post-Translational - drug effects; Protein Tyrosine Phosphatases - antagonists & inhibitors; Protein Tyrosine Phosphatases - physiology; Protein-Tyrosine Kinases - metabolism; Proto-Oncogene Proteins; src-Family Kinases - antagonists & inhibitors; Stromal Cells - cytology; Stromal Cells - physiology; Transfusions. Complications. Transfusion reactions. Cell and gene therapy; Erythropoiesis; Human; Erythroid cell; Enzyme; Transferases; Phosphoric monoester hydrolases; Red blood cell; Esterases; Cell differentiation; Inactivation; Blood; Blood cell; Hydrolases; Umbilical cord; Protein-tyrosine kinase; Protein-tyrosine-phosphatase
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2002-03-0864

CD45 is a membrane-associated tyrosine phosphatase that dephosphorylates Src family kinases and Janus kinases (JAKs). To clarify the role of CD45 in hematopoietic differentiation, we examined the effects of anti-CD45 monoclonal antibody NU-LPAN on the proliferation and differentiation of umbilical cord blood CD34+ cells. NU-LPAN showed a prominent inhibition of the proliferation of CD34+ cells induced by the mouse bone marrow stromal cell line MS-5 or erythropoietin (EPO). However, NU-LPAN did not affect the proliferation induced by interleukin 3. NU-LPAN also inhibited MS-5–induced or EPO-induced erythroid differentiation of CD34+ cells. The cells stimulated with EPO in the presence of NU-LPANmorphologically showed differentiation arrest at the stage of basophilic erythroblasts after 11 days of culture, whereas the cells treated with EPO without NU-LPAN differentiated into mature red blood cells. The Src family kinase Lyn and JAK2 were phosphorylated when erythroblasts obtained after 4 days of culture of CD34+ cells in the presence of EPO were restimulated with EPO. Overnight NU-LPAN treatment before addition of EPO reduced the phosphorylation of Lyn but not that of JAK2. Simultaneously, the enhancement of Lyn kinase activity after restimulation with EPO was reduced by NU-LPAN treatment. These results indicate selective inactivation of Lyn by CD45 activated with NU-LPAN and could partly explain the inhibitory mechanism on erythropoiesis exhibited by EPO. These findings suggest that CD45 may play a pivotal role in erythropoiesis.