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Some characteristics of natural cytostatic mouse splenocytes
Abstract:
Murine B16 melanoma cells and metastasis variants of this tumor are resistant to NK activity mediated by normal splenocytes. The B16 cells are, however, sensitive to splenocyte-mediated cytostasis. Cytostasis was measured by a [125I]UDR incorporation-inhibition [(125I]UDR I-I) assay. The main characteristics of the [125I[UDR I-I assay and of the cells mediating it are as follows: The activity is mediated by splenocytes but not by thymocytes, it is not syngeneically restricted and it does not decrease with age. The presence of effector cells is required as splenocyte supernatants or supernatants of effector-target cell mixtures do not cause [125I]UDR I-I. The activity is probably mediated by at least 2 populations of non-phagocytic splenocytes. The first population adheres to plastic surfaces and to Sephadex G-10 columns while the other does not. The sensitivity to [125I]UDR I-I of the high metastasis B16 variant was similar to that of the low metastasis variant.
Insights
Murine B16 melanoma cells resist natural killer (NK) cell activity but are sensitive to splenocyte-mediated cytostasis. This study characterizes the splenocytes responsible for this cytostatic effect.
Area of Science:
- Immunology
- Cancer Biology
- Cell Biology
Background:
- Murine B16 melanoma cells exhibit resistance to natural killer (NK) cell-mediated lysis.
- These tumor cells are, however, susceptible to splenocyte-mediated cytostasis.
Purpose of the Study:
- To characterize the splenocyte-mediated cytostasis assay ([125I]UDR I-I) and identify the effector cells involved.
- To investigate the characteristics of splenocytes that inhibit B16 melanoma cell proliferation.
Main Methods:
- Utilized the [125I]UDR incorporation-inhibition ([125I]UDR I-I) assay to measure cytostasis.
- Evaluated effector cell populations, including splenocytes and thymocytes, and assessed the role of cell adherence and age.
- Compared the sensitivity of high and low metastasis B16 variants to this cytostatic activity.
Main Results:
- Splenocytes, but not thymocytes, mediated cytostasis against B16 melanoma cells.
- The cytostatic activity was not restricted by the mouse's genetic background (syngeneic) and did not decline with age.
- Effector cell presence was necessary; cell-free supernatants did not induce cytostasis.
- At least two distinct populations of non-phagocytic splenocytes were implicated, differing in their adherence properties.
- Both high and low metastasis B16 variants showed similar sensitivity to this splenocyte-mediated cytostasis.
Conclusions:
- Splenocytes possess a non-NK mediated cytostatic activity against B16 melanoma cells.
- This activity is mediated by distinct, non-phagocytic splenocyte populations.
- The characterized cytostasis assay provides a method to study these specific immune cell interactions in cancer.