Emperipolesis observed in immature cells in blast crisis of chronic myelogenous leukaemia
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Abstract:
In a 62 year-old male with chronic myelogenous leukaemia, an acute phase developed with appearance of large immature cells in the bone marrow. A significant proportion of these cells was found to have engulfed autologous immature and polymorphonuclear neutrophils, erythroblasts, red cells and platelets. These abnormal cells were Philadelphia chromosome positive, and considered to be derived from the leukaemic cell line. Electron microscopic examinations revealed, in the cytoplasm of engulfed cells, no lysosomes or phagosomes which are typically seen in phagocytic cells, nor any evidence of degenerative changes in either engulfing or engulfed cells. These findings suggest that this phenomenon be considered as emperipolesis rather than phagocytosis. The pathophysiological mechanism of this phenomenon is uncertain.
Insights
In chronic myelogenous leukemia, abnormal Philadelphia chromosome-positive cells engulfed other blood cells without signs of digestion. This cellular interaction is identified as emperipolesis, not phagocytosis, with an uncertain underlying mechanism.
Area of Science:
- Hematology
- Oncology
- Cell Biology
Background:
- Chronic myelogenous leukemia (CML) is a myeloproliferative neoplasm characterized by the Philadelphia chromosome.
- Acute phase transformation in CML involves the emergence of immature blast cells.
- Cellular interactions in bone marrow can involve phagocytosis, where cells engulf and digest other cells.
Observation:
- In a patient with CML in acute phase, large immature cells were identified in the bone marrow.
- These abnormal cells were Philadelphia chromosome-positive and presumed to originate from the leukemic clone.
- A significant number of these leukemic cells were observed to contain intact, non-digested autologous cells, including neutrophils, erythroblasts, red blood cells, and platelets.
Findings:
- Electron microscopy revealed no lysosomes or phagosomes within the engulfing cells, differentiating the process from typical phagocytosis.
- No degenerative changes were observed in either the engulfing leukemic cells or the engulfed blood cells.
- The observed phenomenon was characterized as emperipolesis, a non-lytic interaction where one cell penetrates another.
Implications:
- This case highlights emperipolesis as a distinct cellular interaction occurring in the context of CML acute phase.
- The findings suggest that leukemic cells can engage in emperipolesis, potentially impacting hematopoiesis.
- Further research is needed to elucidate the pathophysiological mechanisms and clinical significance of emperipolesis in leukemia.