Which marker indicates the presence of immature lymphocytes?

The presence of immature lymphocytes is indicated by the expression of Terminal deoxynucleotidyl transferase (TdT). TdT is an enzyme that is typically expressed in the early stages of lymphocyte development, particularly during the differentiation of lymphocytes in the bone marrow. This marker is significant in identifying leukemias and lymphomas, especially in distinguishing between acute lymphoblastic leukemia (ALL) and other types of leukemias.

Immature lymphocytes, such as B and T precursor cells, exhibit TdT expression, which helps to differentiate them from mature lymphocytes that typically do not express this enzyme. Understanding this marker is crucial for cytometry practices, as it aids in diagnosing hematological malignancies and identifying the maturation stage of lymphocytes in various clinical contexts.