Myeloblast and Lymphoblast

During the early stages of differentiation, pluripotent hematopoietic stem cells give rise to various committed progenitor cells. These include cells dedicated to forming red blood cells and two primary white blood cell lineages: the myelocytic and lymphocytic lineages. The myelocytic lineage starts with the myeloblast, while the lymphocytic lineage begins with the lymphoblast.

1.0Genesis of the White Blood Cells

2.0Myeloblast 

• The myelocytic lineage of WBC begins with the myeloblast.
• They are immature cells formed in bone marrow that undergo granulopoiesis and become mature granulocytes.
• These are the precursor cells of eosinophil, neutrophil and basophil.
• The earliest identifiable granulocyte precursor is the myeloblast, a minimally granulated cell with scant cytoplasm and a prominent nucleus.

3.0Lymphoblast

• The lymphocytic lineage of WBC  begins with the lymphoblast.
• They are immature cells formed in bone marrow which undergo lymphopoiesis to become mature lymphocytes.
• These are the precursor cells of B lymphocytes, T lymphocytes, and natural killer (NK) cells.
• Naive lymphocytes are typically considered to have a short lifespan. When exposed to specific cytokines and antigens, these lymphocytes are prompted to exit their resting state (G0) and enter the cell cycle, progressing through the G1, S, G2, and M phases. During this process, they grow into larger 15-µm lymphoblasts, which exhibit a higher cytoplasm-to-nucleus ratio and increased organelle complexity compared to their smaller resting counterparts.
• Lymphoblasts proliferate and eventually differentiate into effector cells or memory cells.

4.0Myeloblast vs. Lymphoblast

5.0Disorders

• Acute Myeloid Leukemia (AML) is a cancer of hematopoietic stem cells caused by acquired genetic mutations that block normal cell differentiation. This results in the buildup of immature myeloid blasts in the bone marrow.
• Acute Lymphoblastic Leukemia/Lymphoma (ALL) is a malignancy involving B or T lymphoblasts, marked by the uncontrolled proliferation of abnormal, immature lymphocytes and their precursors.