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Granulocytic colonies on macrophage-coated cellulose acetate membranes (CAM) in S1/S1dmice
Abstract:
The kinetics of formation of granulocytic colonies on macrophage-coated cellulose acetate membranes (CAM) were investigated in Sl/Sld mice, which have a genetic defect in their hematopoietic microenvironment. CAM were left in the peritoneal cavity of mice for 7 days to become coated with peritoneal cells. The mice were then sublethally irradiated to suppress endogenously derived granulocytic colonies, and bone marrow cells were injected i.p. within 1--2 hr irradiation. During the next 7 days, peroxidase-positive granulocytic colonies appeared on CAM. The number of colonies on CAM in Sl/Sld mice at 7 days was consistently less than that from littermate +/+ mice. Since it appeared that the CAM in the Sl/Sld provided an inferior microenvironment to that of the +/+, the effect of raising a CAM in one genotype and transferring it to another was investigated. CAM raised in +/+ or in Sl/Sld were transferred to an irradiated +/+ or Sl/Sld following which cells were injected into the secondary host and colonies determined subsequently. The number of granulocytic colonies on CAM was influenced primarily by the type of secondary host. Colony number was consistently less in the secondary Sl/Sld host than in the +/+ host whether the primary host was a Sl/Sld or a +/+. These observations confirm the concept of a microenvironmental defect in Sl/Sld mice. In addition, the studies indicate that the microenvironment on a CAM can be modified by a secondary host and suggest that "remodeling" of CAM may be a continuous, kinetic process.
Insights
Hematopoietic microenvironment defects in Sl/Sld mice impair granulocytic colony formation. The secondary host environment significantly influences colony numbers on macrophage-coated membranes, confirming a microenvironmental defect.
Area of Science:
- Hematology
- Immunology
- Stem Cell Biology
Background:
- Sl/Sld mice possess a genetic defect affecting their hematopoietic microenvironment.
- Macrophage-coated cellulose acetate membranes (CAM) can serve as a model to study hematopoietic cell interactions.
- Investigating colony formation kinetics provides insights into microenvironmental influences.
Purpose of the Study:
- To investigate the kinetics of granulocytic colony formation on CAM in Sl/Sld mice.
- To determine if the microenvironment of CAM is influenced by the host genotype.
- To confirm the concept of a microenvironmental defect in Sl/Sld mice.
Main Methods:
- CAM were implanted in mice for 7 days to acquire peritoneal cells.
- Mice were irradiated and injected with bone marrow cells.
- Granulocytic colonies on CAM were quantified over 7 days.
- CAM were transferred between genotypes to assess host influence.
Main Results:
- Sl/Sld mice showed fewer granulocytic colonies on CAM compared to +/+ mice.
- CAM raised in either genotype and transferred to secondary hosts revealed a primary influence of the secondary host.
- Colony numbers were consistently lower in Sl/Sld secondary hosts, irrespective of the primary host genotype.
Conclusions:
- The results confirm a microenvironmental defect in Sl/Sld mice affecting granulopoiesis.
- The host environment significantly modifies the CAM microenvironment.
- CAM remodeling appears to be a continuous kinetic process influenced by the host.