Functional channel formation associated with cytotoxic T-cell granules.
Lymphocyte granules from cytotoxic T-lymphocyte lines A2, A11, and R8 were enriched by subcellular fractionation using a Percoll gradient. Granule-enriched fractions showed potent hemolytic activity in the presence of Ca2+. Isolated granules induced rapid Ca2+-dependent membrane depolarization of J774 macrophage-like cells. When tested in planar bilayers, granules induced the formation of Ca2+-dependent functional ion channels of large conductance steps of 1-6 nS in 0.1 M NaCl. Granule-induced channels were resistant to closing by an increase in transmembrane potential, with few channels shifting to the closed state only at voltages of greater than 70 mV, following a Poisson process. These channels showed poor ion selectivity and were permeable to all monovalent and divalent ions (K+, Na+, Li+, Cl-, Ca2+, Mg2+, Zn2+, Ba2+). Ultrastructural examination of soluble granule proteins incubated for 48 hr at 37 degrees C in the presence of Ca2+ revealed ring-like structures of 150-200 A. Structural and functional channel formation may be involved in cytolysis induced by cytotoxic T lymphocytes.
J D
JD
Young
C F
CF
Nathan
E R
ER
Podack
M A
MA
Palladino
Z A
ZA
Cohn
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002458:Cell Fractionation; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D002463:Cell Membrane Permeability; D003594:Cytoplasmic Granules / Q000502:physiology*; D004553:Electric Conductivity; D004912:Erythrocytes / Q000648:ultrastructure; D006461:Hemolysis; D007473:Ion Channels / Q000502:physiology*; D007477:Ions; D008051:Lipid Bilayers; D008264:Macrophages / Q000502:physiology; D008563:Membrane Lipids / Q000502:physiology; D008564:Membrane Potentials; D051379:Mice; D008810:Mice, Inbred C57BL; D013602:T-Lymphocytes, Cytotoxic / Q000648:ultrastructure*
D007473:Ion Channels; D007477:Ions; D008051:Lipid Bilayers; D008563:Membrane Lipids; D002118:Calcium