Lymphocytes from a normal individual were stimulated in vitro by coculture with
ID: 90118 • Letter: L
Question
Lymphocytes from a normal individual were stimulated in vitro by coculture with irradiated T lymphoma cells. (Irradiation of these stimulator cells prevents them from dividing in the coculture.) After 7 days, the lymphocytes were harvested and fractionated to obtain a population of cytotoxic Tcells (CD8+). These effector cells were set up in a cytotoxicity assay with the tumour cells as targets. The tumours cells were labeled, in order to detect both DNA fragmentation and cell lysis. The following results were obtained in these assays: Why do the Tc cells lyse the targets and induce DNA fragmentation? What are these cells recognizing on the tumour cell surface?Explanation / Answer
Cytotoxic Tcells kill there targets by programming them to undergo Apoptosis.when cytotoxic Tcells are mixed with target cells and rapidly brought into contact by centrifugation they can program cells to die with in 5 min , although dealth may take hours to become fully evident.
The short period required bY cytotoxic Tcells to program there targets to die reflect the release of performed effortor molecules which activate an endogenous apoptotic pathway with in target cell.
Cytotoxic Tcells can Induced apoptosis in target cells by specific recognition of peptide MHC complexes on a target cell by a cytotoxic CD8 Tcells leads to the target cells by apoptosis.
They recycle to kill multiple target each killing requires same series of steps, including receptor binding and directed release of cytotoxic proteins stored in lytic granules.
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