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I. Increase in bone marrow CFU-S and CFU-C after in vivo phytohaemagglutinin (PHA) administration in mice
Abstract:
An absolute increase in bone marrow CFU-S was observed within 4 hours after intraperitoneal administration of 3 mg PHA-M or 250 microgram PHA-P. At that time, there was no increase in spleen CFU-S, while a pronounced decrease in the number of circulating CFU-S was noted. A two to fourfold increase in bone marrow CFU-C was found within 12 hours after intraperitoneal administration of a similar dose of PHA-M or PHA-P. Addition of PHA-M or PHA-P at small concentrations resulted in a marked inhibition of granulocytic colony formation whereas macrophage colony growth became depressed only at very high concentrations.
Insights
Phytohemagglutinin (PHA) administration rapidly increased bone marrow stem cells but decreased circulating stem cells. PHA also affected colony-forming cells, inhibiting granulocytic formation more than macrophage formation.
Area of Science:
- Hematology
- Immunology
- Pharmacology
Background:
- Phytohemagglutinin (PHA) is a lectin known to stimulate lymphocyte proliferation.
- Understanding PHA's effects on hematopoietic stem cells is crucial for its therapeutic and toxicological evaluation.
Purpose of the Study:
- To investigate the acute effects of PHA-M and PHA-P on hematopoietic stem and progenitor cells in vivo.
- To determine the dose-dependent effects of PHA on granulocytic and macrophage colony formation in vitro.
Main Methods:
- Intraperitoneal administration of PHA-M and PHA-P to mice.
- Quantification of bone marrow, spleen, and circulating CFU-S (colony-forming units-spleen) at various time points.
- In vitro culture of bone marrow cells with PHA-M and PHA-P to assess colony formation.
Main Results:
- An absolute increase in bone marrow CFU-S was observed within 4 hours post-administration.
- A decrease in circulating CFU-S and no significant change in spleen CFU-S were noted at 4 hours.
- Bone marrow CFU-C (colony-forming cells) showed a two to fourfold increase within 12 hours.
- Low concentrations of PHA inhibited granulocytic colony formation, while macrophage colony formation was only affected at very high concentrations.
Conclusions:
- PHA induces rapid mobilization and proliferation of hematopoietic stem cells in the bone marrow.
- PHA exhibits differential effects on myeloid progenitor cells, with a more pronounced inhibition of granulocytic precursors.
- These findings highlight PHA's complex impact on hematopoiesis, with implications for its use in research and potential clinical applications.
