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Characterization of the effector cells responsible for tumour resistance in Salmonella enteritidis 11RX-immunized
Abstract:
In an attempt to characterize the effector cells responsible for tumour resistance in Salmonella enteritidis 11RX-immunized mice the anti-macrophage agent trypan blue was used in both in vivo and in vitro experiments. Resistance was measured in vivo by the clearance of 125I from the peritoneal cavity of mice injected intraperitoneally with 125I-5-iododeoxyuridine labelled Ehrlich Ascites Tumour (EAT) cells. The in vitro correlate was measured by lysis of 51Cr-labelled tumour cells by peritoneal cells (PC) from 11RX-immunized mice. Pre-treatment of resistant mice with trypan blue greatly reduced both 125I clearance and 51Cr release. The in vitro cytolytic activity was non-specific. Fractionation of cytotoxic PC on the basis of adherence to plastic or nylon wool and buoyant density, coupled with the use of appropriate cell targets, showed that the bulk of cytotoxic activity resided with macrophages, with some contribution from other cells such as natural killer cells. Killing of labelled tumour cells could be inhibited by competition with unlabelled cells or by separating the PC and tumour cells by a cell impermeable membrane. This showed that close association between the effector and target cells was necessary before killing could occur.
Insights
Tumor resistance in mice immunized with Salmonella enteritidis involves macrophages. These effector cells mediate tumor cell killing through direct contact, crucial for the anti-tumor immune response.
Area of Science:
- Immunology
- Cancer Research
- Microbiology
Background:
- Salmonella enteritidis immunization confers tumor resistance in mice.
- Identifying the specific immune cells responsible for this resistance is crucial for understanding anti-tumor immunity.
Purpose of the Study:
- To characterize the effector cells mediating tumor resistance in Salmonella enteritidis-immunized mice.
- To investigate the role of macrophages in anti-tumor immunity.
Main Methods:
- In vivo and in vitro experiments using the anti-macrophage agent trypan blue.
- Measuring tumor resistance via clearance of radiolabeled tumor cells (125I-5-iododeoxyuridine) from the peritoneal cavity.
- Assessing in vitro tumor cell lysis (51Cr release) by peritoneal cells from immunized mice.
Main Results:
- Trypan blue pre-treatment significantly reduced tumor cell clearance in vivo and tumor cell lysis in vitro.
- Fractionation of peritoneal cells indicated that macrophages are the primary cytotoxic effector cells, with a contribution from natural killer cells.
- Tumor cell killing required close cell-to-cell contact, as evidenced by inhibition experiments.
Conclusions:
- Macrophages are the principal effector cells responsible for tumor resistance induced by Salmonella enteritidis immunization.
- The anti-tumor immune response involves direct cell-mediated cytotoxicity requiring close interaction between effector and target cells.