A noncytotoxic mast cell tumor line exhibits potent IgE-dependent cytotoxicity after transfection with the cytolysin/perforin gene.
To test the granule exocytosis model for lymphocyte cytotoxicity, we have expressed the gene for the cytotoxic lymphocyte granule protein cytolysin (perforin) in the noncytotoxic rat basophilic leukemia (RBL) cell line, which undergoes granule exocytosis when its high affinity IgE receptor is cross-linked. Homogenates of RBL-cytolysin (RBL-cy) transfectants showed a calcium-dependent hemolytic activity in dense granule fractions, demonstrating that the expressed cytolysin protein was correctly targeted to secretory granules. RBL-cy transfectants showed a potent and calcium-dependent cytolytic activity against IgE-coated RBCs, while the parental RBL line was not cytotoxic under these conditions. RBL-cy cells did not lyse non-IgE-coated RBCs copelleted with targets: this sparing of "innocent bystanders" parallels cytotoxic T lymphocyte lysis and suggests a polarized secretion of cytolysin. In contrast to RBC targets, IgE-coated tumor cells were much less sensitive to lysis by RBL-cy transfectants.
Shiver
J W
JW
Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
Henkart
P A
PA
D000920:Antibody-Dependent Cell Cytotoxicity / Q000502:physiology*; D004912:Erythrocytes / Q000502:physiology; D005089:Exocytosis / Q000276:immunology*; D007073:Immunoglobulin E / Q000502:physiology; D015471:Leukemia, Basophilic, Acute; D008407:Mast Cells / Q000378:metabolism*; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D013602:T-Lymphocytes, Cytotoxic / Q000502:physiology*; D014162:Transfection; D014407:Tumor Cells, Cultured
D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin; D007073:Immunoglobulin E