TY - JOUR
T1 - Membrane channel formation by the lymphocyte pore-forming protein
T2 - Comparison between susceptible and resistant target cells
AU - Persechini, Pedro M.
AU - Young, John Ding E.
AU - Almers, Wolfhard
PY - 1990/6
Y1 - 1990/6
N2 - The assembly of pores by the pore-forming protein (perforin) of cytolytic T lymphocytes (CTLs) and natural killer cells on the membranes of different cell lines was studied. Using the patch clamp technique in the whole cell configuration, we measured the conductance increase induced by perforin in susceptible cell lines as well as in resistant CTL lines (CTLLs). The results showed that although the amplitudes of the first observed conductance steps produced in both cell types were comparable, CTLLs required at least 10-fold higher doses of perforin to form membrane pores. Outside-out patches excised from CTLL-R8, on the other hand, appeared to be more susceptible to channel formation by perforin than intact cells, as lower doses were able to induce conductance increases. Once channels were induced in CTL membranes, however, their conductances (>1 nS) were indistinguishable from the ones obtained in susceptible cell lines. Fluorescence measurements with quin-2 showed that perforin induced rapid increases in the intracellular Ca2+ concentration in susceptible EL4 cells. In marked contrast, a perforin dose 60-120-fold higher than the minimal dose required to elicit Ca2+ changes in EL4 cells was not able to induce any measurable Ca2+ increase in CTLL-R8. The data suggest that the resistance of CTLs to lysis mediated by their own mediator perforin is at least in part due to their ability to avoid pore formation by this protein. The mechanism underlying this phenomenon is not yet understood, but the observation that outside-out patches excised from CTLL-R8 are more susceptible to channel formation by perforin than intact cells raises the possibility that an intracellular mechanism may be involved.
AB - The assembly of pores by the pore-forming protein (perforin) of cytolytic T lymphocytes (CTLs) and natural killer cells on the membranes of different cell lines was studied. Using the patch clamp technique in the whole cell configuration, we measured the conductance increase induced by perforin in susceptible cell lines as well as in resistant CTL lines (CTLLs). The results showed that although the amplitudes of the first observed conductance steps produced in both cell types were comparable, CTLLs required at least 10-fold higher doses of perforin to form membrane pores. Outside-out patches excised from CTLL-R8, on the other hand, appeared to be more susceptible to channel formation by perforin than intact cells, as lower doses were able to induce conductance increases. Once channels were induced in CTL membranes, however, their conductances (>1 nS) were indistinguishable from the ones obtained in susceptible cell lines. Fluorescence measurements with quin-2 showed that perforin induced rapid increases in the intracellular Ca2+ concentration in susceptible EL4 cells. In marked contrast, a perforin dose 60-120-fold higher than the minimal dose required to elicit Ca2+ changes in EL4 cells was not able to induce any measurable Ca2+ increase in CTLL-R8. The data suggest that the resistance of CTLs to lysis mediated by their own mediator perforin is at least in part due to their ability to avoid pore formation by this protein. The mechanism underlying this phenomenon is not yet understood, but the observation that outside-out patches excised from CTLL-R8 are more susceptible to channel formation by perforin than intact cells raises the possibility that an intracellular mechanism may be involved.
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U2 - 10.1083/jcb.110.6.2109
DO - 10.1083/jcb.110.6.2109
M3 - Review article
C2 - 1693622
AN - SCOPUS:0025371943
SN - 0021-9525
VL - 110
SP - 2109
EP - 2116
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 6
ER -