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Analysis of low natural killer cell activity in 89Sr-treated mice
Abstract:
Treatment of mice with the long-lived bone-seeking radioisotope 89Sr results in the selective irradiation and destruction of the bone marrow. This is accompanied by a marked reduction in natural killer cell activity against YAC-1 lymphoma [NK(YAC-1)]. To test for the presence of cellular suppressors of NK(YAC-1) in 89Sr-treated mice, in vitro and in vivo cell mixture protocols were used. In vitro, we did not observe any specific inhibitory effect of spleen cells from 89Sr-treated mice on NK(YAC-1) activity of normal spleen cells. The NK(YAC-1) activity of 89Sr-treated mice, measured in vivo by their ability to clear radiolabeled YAC-1 cells from the lungs, was impaired. However, spleen cells from 89Sr-treated mice, when adoptively transferred with normal spleen cells, failed to inhibit the NK(YAC-1) activity of the latter in the lung clearance assay. Further, when normal spleen cells were injected into 89Sr-treated mice, the ability of the transferred cells to mediate in vivo activity was not suppressed in the 89Sr-treated host. These experiments support the suggestion that the low NK(YAC-1) activity in 89Sr-treated mice is not mediated by suppressor cells, but may be due to the destruction of the marrow microenvironment which is essential for the generation of functional NK(YAC-1) cells.
Insights
Strontium-89 (89Sr) treatment reduces natural killer cell activity by damaging bone marrow, not by introducing suppressor cells. This impairment stems from the destruction of the bone marrow microenvironment essential for natural killer cell development.
Area of Science:
- Immunology
- Radiobiology
- Oncology
Background:
- Strontium-89 (89Sr) is a bone-seeking radioisotope used in cancer therapy.
- 89Sr treatment selectively irradiates bone marrow, leading to reduced natural killer cell activity against YAC-1 lymphoma (NK(YAC-1)).
Purpose of the Study:
- To investigate whether cellular suppressors are responsible for the diminished NK(YAC-1) activity observed in 89Sr-treated mice.
- To elucidate the mechanism behind the reduced NK(YAC-1) function post-89Sr administration.
Main Methods:
- In vitro assays mixing spleen cells from 89Sr-treated and normal mice to assess NK(YAC-1) inhibition.
- In vivo studies involving adoptive transfer of spleen cells and assessment of lung clearance of radiolabeled YAC-1 cells.
- Evaluation of NK(YAC-1) activity in normal spleen cells transferred into 89Sr-treated hosts.
Main Results:
- In vitro spleen cell mixing did not reveal specific inhibition of NK(YAC-1) activity.
- In vivo lung clearance assays showed impaired NK(YAC-1) activity in 89Sr-treated mice.
- Adoptive transfer experiments indicated no suppressor cell activity from 89Sr-treated spleen cells, nor suppression of transferred normal cells within 89Sr-treated hosts.
Conclusions:
- The reduction in NK(YAC-1) activity following 89Sr treatment is not mediated by suppressor cells.
- The impaired natural killer cell function is likely a consequence of the destruction of the bone marrow microenvironment, crucial for NK cell generation.