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In vitro colony-forming characteristics of chronic granulocytic leukemia in childhood
Insights
Adult-type chronic granulocytic leukemia (CGL) in children shows granulocytic colonies, unlike juvenile CGL. This suggests distinct disease forms in pediatric chronic leukemia.
Area of Science:
- Hematology
- Oncology
- Cell Biology
Background:
- Chronic granulocytic leukemia (CGL) presents differently in children compared to adults.
- Distinguishing between juvenile (Ph1 chromosome negative) and adult-type (Philadelphia chromosome positive) CGL is crucial for accurate classification and treatment.
Purpose of the Study:
- To investigate the cellular origin of colony formation in peripheral blood of a child with adult-type CGL.
- To compare the in vitro growth characteristics of adult-type CGL with previously studied juvenile-type CGL.
- To elucidate the distinct nature of these two forms of pediatric chronic leukemia.
Main Methods:
- Isolation of peripheral blood cells from a child with adult-type CGL.
- Colony formation assays in tissue culture.
- Separation of myeloid precursor cells (myeloblasts, promyelocytes, myelocytes) using Ficoll-Hypaque density gradient centrifugation.
Main Results:
- Peripheral blood cells from the child with adult-type CGL formed numerous granulocytic colonies in vitro.
- The source of granulocytic colonies was identified as immature myeloid cells (myeloblasts, promyelocytes, myelocytes).
- This pattern contrasts with juvenile-type CGL, which exclusively produces monocytic colonies.
Conclusions:
- Adult-type CGL in children is a true granulocytic leukemia, characterized by granulocytic colony formation from myeloid precursors.
- Juvenile-type CGL is a monocytic leukemia with a granulocytic component.
- Pediatric CGL encompasses at least two distinct disease entities based on Philadelphia chromosome status and in vitro cellular behavior.
Abstract:
Peripheral blood from a child with adult-type (Philadelphia chromosome positive) chronic granulocytic leukemia was found to contain large numbers of cells capable of colony formation in tissue culture. The majority of the colonies contained granulocytic cells. The source of these granulocytic colonies was found in a population of myeloblasts, promyelocytes, and myelocytes which could be separated from the more mature granulocytic cells of the peripheral blood by sedimentation of the buffy coat on Ficoll-Hypaque. The predominance of granulocytic colonies is in contrast to our observations previously made on the peripheral blood of children with "juvenile" type(Ph1 chromosome negative)CGL in which large numbers of exclusively monocytic colonies were produced in tissue culture. These current studies, when interpreted in light of relevant clinical data, suggest that the "juvenile" and "adult" types of CGL represent two very different forms of chronic leukemia in childhood. The Ph1 chromosome negative form may be classified as a monocytic leukemia with a granulocytic component but the Ph1 chromosome positive adult form, even when it occurs in a child, appears to be a true granulocytic leukemia.