Flow cytometric analysis of Notch1 and Jagged1 expression in normal blood cells and leukemia cells

Notch1 and its ligand Jagged1 are proteins with important roles in the growth of leukemia cells. Although the detection of Notch1 protein in acute lymphoblastic leukemia cells using immunoblot analysis has been previously reported, the expression patterns of Notch1 and Jagged1 detected by flow cytometry (FCM) in normal blood cells and various leukemia cells have not been well-characterised. In the present study, we examined the expression patterns of Notch1 and Jagged1 in 10 normal blood samples, 8 bone marrow samples, 11 leukemia/lymphoma cell lines and leukemia cells from 22 patients with acute myeloid leukemia (AML), mature T-cell neoplasms or B-cell chronic lymphocytic leukemia (B-CLL) using FCM. The results showed that Notch1 expression is relatively strong in monocytes and granulocytes but weak in lymphocytes. The expression of Notch1 is stronger in bone marrow cells than in the equivalent cells in blood. All the cell lines examined strongly expressed Notch1, and eight cell lines expressed Jagged1. In leukemia cells from patients, four AML samples expressed Notch1 and/or Jagged1. However, three samples expressed neither Notch1 and/or Jagged1 and none of the mature T-cell neoplasm samples expressed either protein. However, all B-CLL samples expressed high levels of both Notch1 and Jagged1. We found that the expression of Notch1 and Jagged1 is detected in various hematological malignancies by FCM. The examination of these proteins is likely to be useful in the characterisation of diseases and individual cases. Examination of these proteins may also be useful in the selection of patients most likely to benefit from novel molecular-targeted therapies using Notch inhibitors in the future.