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Stimulation of bone marrow-derived and peritoneal macrophages by a T lymphocyte-derived hemopoietic growth factor,
Abstract:
Several lines of evidence indicated that P cell-stimulating factor (PSF), a T lymphocyte-derived lymphokine known to stimulate the growth of hemopoietic stem and progenitor cells, also acted on macrophages. PSF was absorbed from medium that had been mixed for two hours at 0 degrees C with either resident or thioglycollate-elicited peritoneal cells, suggesting the presence of receptors for PSF on cells in the population. The addition of pure PSF to populations highly enriched in either resident or elicited adherent peritoneal macrophages resulted in stimulation of macrophages with morphological changes, including increases in size, spreading, vacuolation, and the number of cytoplasmic processes, together with stimulation of proliferation and the phagocytosis of opsonized yeast. PSF also stimulated the incorporation of [3H]thymidine by bone marrow-derived adherent macrophages. Addition of pure PSF to cultures that contained only a single macrophage resulted in enhanced survival and proliferation of these isolated cells, demonstrating that the effect of PSF on macrophages was direct. These results indicate that PSF can stimulate well-differentiated functional macrophages and raise the possibility that the effects of PSF on macrophages may play a regulatory role in immune responses.
Insights
P cell-stimulating factor (PSF), a T lymphocyte-derived lymphokine, directly stimulates macrophages. This finding suggests PSF plays a regulatory role in immune responses by enhancing macrophage function and survival.
Area of Science:
- Immunology
- Cell Biology
Background:
- P cell-stimulating factor (PSF) is a lymphokine derived from T lymphocytes.
- PSF is known to stimulate hemopoietic stem and progenitor cells.
- Evidence suggested PSF might also affect macrophages.
Purpose of the Study:
- To investigate the direct effects of PSF on macrophages.
- To determine if macrophages possess receptors for PSF.
- To explore PSF's role in macrophage function and immune regulation.
Main Methods:
- Incubation of peritoneal cells with PSF to assess absorption and receptor presence.
- Treatment of enriched macrophage populations with pure PSF.
- Assessment of macrophage morphology, proliferation, and phagocytosis.
- Stimulation of [3H]thymidine incorporation in bone marrow-derived macrophages.
- Culture of single macrophages with PSF to confirm direct effects.
Main Results:
- PSF was absorbed by peritoneal cells, indicating receptor presence.
- PSF induced morphological changes in macrophages, including increased size and cytoplasmic processes.
- PSF stimulated macrophage proliferation and phagocytosis of opsonized yeast.
- PSF enhanced [3H]thymidine incorporation in bone marrow-derived macrophages.
- PSF directly promoted the survival and proliferation of isolated macrophages.
Conclusions:
- PSF directly acts on well-differentiated functional macrophages.
- PSF enhances macrophage survival, proliferation, and phagocytic activity.
- PSF's effects on macrophages suggest a potential regulatory role in immune responses.