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Metabolic inhibitors render "resistant" target cells sensitive to natural killer cell-mediated lysis
Abstract:
L-929 cells were lysed by activated but not by endogenous natural killer (NK) cells, as reported previously. Nevertheless, L-929 cells bound to endogenous NK cells, as shown by target binding cell, cold target competition, and monolayer absorption assays. Treatment of L-929 cells with actinomycin-D or cycloheximide rendered them sensitive to lysis by endogenous NK cells and markedly increased their sensitivity to lysis by activated NK cells. Treatment with these drugs under the prescribed conditions did not affect the binding of L-929 cells to NK cells. Since others have shown that treatment with these drugs inhibits membrane repair processes and renders cells more sensitive to complement-mediated lysis, we hypothesize that membrane repair may be an important factor influencing a cell sensitivity to NK cells. This may be more important than NK-binding ability, since most cells can be lysed by (and therefore bind to) activated NK cells.
Insights
Cell membrane repair, not just binding, influences natural killer (NK) cell sensitivity. Inhibiting repair mechanisms makes cells more vulnerable to NK cell lysis, highlighting a new factor in immune response.
Area of Science:
- Immunology
- Cell Biology
Background:
- L-929 cells were previously shown to be lysed by activated but not endogenous natural killer (NK) cells.
- L-929 cells demonstrate binding capabilities with endogenous NK cells, confirmed through various binding assays.
Purpose of the Study:
- To investigate the factors influencing L-929 cell sensitivity to NK cell-mediated lysis.
- To determine if membrane repair mechanisms play a role in NK cell cytotoxicity.
Main Methods:
- L-929 cells were treated with actinomycin-D or cycloheximide to inhibit membrane repair.
- Cell binding assays (target binding, cold target competition, monolayer absorption) were used to assess NK cell interaction.
- Cytotoxicity assays were performed to measure L-929 cell lysis by both endogenous and activated NK cells.
Main Results:
- Drug treatment did not affect L-929 cell binding to NK cells.
- Inhibition of membrane repair by actinomycin-D or cycloheximide significantly increased L-929 cell sensitivity to lysis by both endogenous and activated NK cells.
- This suggests membrane repair is a critical factor in NK cell susceptibility.
Conclusions:
- Cellular membrane repair mechanisms are crucial in determining sensitivity to natural killer (NK) cell lysis.
- The ability of a cell to repair its membrane may be more critical than its binding affinity to NK cells for survival.
- These findings offer new insights into NK cell-mediated cytotoxicity and cellular defense mechanisms.