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Leucocyte alkaline phosphatase elevation in human acute leukaemia derived cell lines cultured in diffusion chambers
Abstract:
Leucocyte alkaline phosphatase (LAP) was histochemically detected in 7 to 18% of cells in tissue culture lines derived from the peripheral blood or bone marrow of each of 5 patients with untreated acute myelogenous or monomyelogenous leukaemia and in 30% of the cells in a clonal line of a rat promyelocytic leukaemia. Following transfer to diffusion chambers intraperitoneally implanted into total body irradiated rats, LAP levels were detected in up to 92% of human and 80% of rat leucocytes. There was no associated morphologic differentiation. In rat leukaemia cells peroxidase and myeloid specific esterase also increased from tissue culture levels. Return of cells to tissue culture decreased enzymes to pre-implant levels. Addition of plasma or peritoneal fluid from irradiated rats to cells in tissue culture again induced LAP. In contrast, LAP was not increased under these conditions with cell lines derived from patients with acute lymphatic leukaemia, or Sezary cell leukaemia. These studies indicate that a humoral factor in peritoneal fluid and plasma of irradiated rats increases LAP in human as well as rat leucocytes.
Insights
A humoral factor in irradiated rats significantly increases leucocyte alkaline phosphatase (LAP) in both human and rat leukemia cells. This factor, found in plasma and peritoneal fluid, boosts LAP without causing cell differentiation.
Area of Science:
- Hematology
- Cell Biology
- Biochemistry
Background:
- Leukocyte alkaline phosphatase (LAP) is an enzyme found in leukocytes.
- LAP levels can vary in different types of leukemia.
- Previous studies suggested a potential role for external factors in modulating LAP activity.
Purpose of the Study:
- To investigate the effect of a humoral factor from irradiated rats on LAP levels in leukemia cells.
- To determine if this factor induces differentiation in leukemia cells.
- To identify the source and nature of the humoral factor.
Main Methods:
- Establishing tissue culture lines from human acute myelogenous/monomyelogenous leukemia and rat promyelocytic leukemia.
- Implanting leukemia cells into diffusion chambers in irradiated rats.
- Measuring LAP activity histochemically in cells before and after implantation.
- Analyzing peroxidase and myeloid specific esterase activity in rat leukemia cells.
- Testing the effect of plasma and peritoneal fluid from irradiated rats on leukemia cells in vitro.
Main Results:
- LAP levels increased significantly (up to 92% in human, 80% in rat cells) after implantation in irradiated rats.
- No morphological differentiation was observed in the leukemia cells.
- Peroxidase and myeloid specific esterase also increased in rat leukemia cells.
- LAP levels returned to baseline upon return to tissue culture.
- Plasma and peritoneal fluid from irradiated rats induced LAP in vitro.
Conclusions:
- A humoral factor present in the plasma and peritoneal fluid of irradiated rats stimulates LAP activity in both human and rat leukemia cells.
- This factor does not induce morphological differentiation.
- The observed increase in LAP is reversible and dependent on the presence of the humoral factor.