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Fractionation of untreated and inflammatory murine peritoneal macrophages on discontinuous Percoll density gradients
Abstract:
Peritoneal cells from C57/BL/6J mice untreated or injected with saline, proteose-peptone or Corynebacterium parvum intraperitoneally or Sauton medium or BCG intravenously were fractionated on discontinuous Percoll gradients. Six subsets of macrophages were obtained in all the groups. Injection of BCG and proteose-peptone increased the percentage of heavy density macrophages whereas C. parvum caused an increase in macrophages in the lighter density fractions. The macrophages in all the subsets were tested for their ability to kill L929 target cells and cytochemically for expression of beta-galactosidase. The highest degree of cytotoxicity was found in the higher density subsets, although the other subsets in the C. parvum group were also cytotoxic. There was a marked reduction in beta-galactosidase in macrophages obtained after injection of C. parvum and to a varying degree after injection of BCG, proteose-peptone or saline. Cells which were devoid of enzyme were evenly distributed throughout the subsets. These studies indicate that a certain degree of separation of cytotoxic macrophages can be achieved by density centrifugation, but not of cells containing different amounts of beta-galactosidase.
Insights
Density gradient centrifugation separates cytotoxic macrophages from mouse peritoneal cells. Different treatments altered macrophage density, with some subsets showing higher cytotoxicity but not specific beta-galactosidase levels.
Area of Science:
- Immunology
- Cell Biology
- Macrophage Biology
Background:
- Macrophages play a crucial role in cellular immunity and host defense.
- Macrophage heterogeneity exists, with distinct subsets possessing varying functional capacities.
- Understanding macrophage subsets is key to developing targeted immunotherapies.
Purpose of the Study:
- To investigate the separation of cytotoxic macrophages using density gradient centrifugation.
- To analyze the effect of different intraperitoneal or intravenous injections on macrophage density and function.
- To correlate macrophage density and beta-galactosidase expression with cytotoxic activity.
Main Methods:
- Peritoneal macrophages were isolated from C57/BL/6J mice subjected to various treatments (saline, proteose-peptone, Corynebacterium parvum, Sauton medium, BCG).
- Macrophages were fractionated using discontinuous Percoll gradients to obtain distinct density subsets.
- Cytotoxicity against L929 target cells and beta-galactosidase expression were assessed in each subset.
Main Results:
- Six macrophage subsets were consistently obtained across all treatment groups.
- BCG and proteose-peptone injections increased heavy density macrophages, while C. parvum increased light density macrophages.
- Higher density subsets exhibited the greatest cytotoxicity; beta-galactosidase levels were reduced following C. parvum, BCG, proteose-peptone, or saline injections.
Conclusions:
- Density centrifugation can partially separate cytotoxic macrophage populations.
- Macrophage density is influenced by specific in vivo stimuli.
- Beta-galactosidase expression does not directly correlate with macrophage density or cytotoxic potential in this model.