Related Experiment Videos
Blocking of lymphokine activated killer (LAK) cell mediated cytotoxicity by cell-sized beads bearing tumor cell
A S Chong1, E M Hersh, W J Grimes
1Department of Biochemistry, Arizona Cancer Center, Tucson 85721.
Abstract:
Lymphokine activated killer cells (LAK) have been demonstrated to be cytotoxic for a variety of tumor-derived cells. Little is known of the nature of the cell surface molecules that mediate LAK cell-target cell interactions. Reported here are studies designed to develop the methodology that can lead to the identification and characterization of tumor cell surface molecules recognized by LAK cells. Results from experiments involving the pre-treatment of LAK cells and target cells (51Cr-labeled target cells or cold-blocking cells) with trypsin, neuraminidase, or sodium periodate suggest that proteins on the surface of LAK cells specifically recognized trypsin-sensitive molecules on the tumor cell surface. We extracted tumor cell membranes with detergents, and incorporated membrane proteins together with phospholipids and cholesterol onto the surfaces of cell-sized hydrophobic beads. The resulting "pseudocytes" block LAK mediated killing of 51Cr-labeled targets. Trypsin pretreatment of these pseudocytes significantly reduced their blocking activity. These observations suggested that we have incorporated onto the surface of pseudocytes tumor-membrane derived molecules that are specifically recognized by LAK cells. When membrane proteins from LAK resistant PBMC were incorporated onto beads, the resulting pseudocytes did not block LAK mediated cytotoxicity. It is of interest that beads coated with membrane proteins from one tumor were able to reduce LAK cell lysis of a different tumor target. Our results are consistent with the possibility that each LAK cell is polyspecific or that the LAK cell recognizes a common marker on many tumors. The methodology using pseudocytes should allow the purification and characterization of target acceptor molecule(s) and permit us to distinguish between these possibilities.
Insights
Researchers identified tumor cell surface proteins recognized by lymphokine-activated killer (LAK) cells using novel "pseudocyte" technology. These findings advance understanding of LAK cell-tumor interactions and potential cancer therapies.
Area of Science:
- Immunology
- Cell Biology
- Cancer Research
Background:
- Lymphokine-activated killer (LAK) cells exhibit cytotoxicity against various tumor cells.
- The specific cell surface molecules mediating LAK cell-tumor interactions remain largely uncharacterized.
Purpose of the Study:
- To develop and validate a methodology for identifying and characterizing tumor cell surface molecules recognized by LAK cells.
- To investigate the nature of LAK cell-target cell interactions.
Main Methods:
- Utilized enzymatic treatments (trypsin, neuraminidase, sodium periodate) on LAK and target cells to probe surface molecule sensitivity.
- Developed
- pseudocytes
- by incorporating tumor cell membrane proteins, phospholipids, and cholesterol onto hydrophobic beads.
- Assessed the ability of pseudocytes to block LAK-mediated cytotoxicity against labeled tumor targets.
Main Results:
- LAK cell recognition involves trypsin-sensitive molecules on the tumor cell surface.
- Pseudocytes incorporating tumor membrane proteins blocked LAK-mediated killing, with activity reduced upon trypsin pretreatment.
- Membrane proteins from LAK-resistant cells did not block LAK activity, indicating specificity.
- Pseudocytes derived from one tumor could inhibit LAK cell lysis of a different tumor target.
Conclusions:
- The developed pseudocyte methodology effectively incorporates tumor-specific LAK-recognized molecules.
- Results suggest LAK cells may be polyspecific or recognize common tumor markers.
- This approach facilitates the purification and characterization of LAK cell target acceptor molecules.