TY - JOUR
T1 - Serial killing by cytotoxic T lymphocytes
T2 - T cell receptor triggers degranulation, re‐filling of the lytic granules and secretion of lytic proteins via a non‐granule pathway
AU - Isaaz, Sylvie
AU - Baetz, Kristin
AU - Olsen, Kristin
AU - Podack, Eckhard
AU - Griffiths, Gillian M.
PY - 1995/4
Y1 - 1995/4
N2 - CD8+ cytotoxic T lymphocyte (CTL) clones begin to synthesize the lytic proteins granzyme A, granzyme B and perforin after stimulation with allogenic target cells. The lytic proteins are stored in the secretory granules which are released after cross-linking of the T cell receptor (TcR) upon target cell recognition. During lytic granule biogenesis granzyme A protein synthesis can be detected between 2 and 10 days after allogenic stimulation of the CTL. Although granzyme A is stored in the lytic granules over this period, the majority of granzyme A synthesized is secreted directly from the CTL. TcR triggering of degranulation also results in new synthesis of the lytic proteins, which can be inhibited by cycloheximide (CHX). Some of the newly synthesized lytic proteins can be stored in the cell and refill the granules. But up to one third of granzymes A and B can be secreted directly from the CTL via the constitutive secretory pathway as shown by granzyme A enzymatic activity and immunoblots of secreted granzyme B, where one third of the protein fails to acquire the granule targeting signal. Perforin is also secreted via the constitutive pathway, both from the natural killer cell line, YT, and from CTL clones after TcR cross-linking. Constitutive secretion of the lytic proteins can be blocked by both CHX and brefeldin A (BFA). While BFA does not affect the directional killing of recognized targets, it abrogates bystander killing, indicating that bystander killing arises from newly synthesized lytic proteins delivered via a non-granule route. These results demonstrate that the perforin/granzyme-mediated lytic pathway can be maintained while CTL kill multiple targets. We show that CTL not only re-fill their granules during killing, but also secrete lytic proteins via a non-granule-mediated pathway.
AB - CD8+ cytotoxic T lymphocyte (CTL) clones begin to synthesize the lytic proteins granzyme A, granzyme B and perforin after stimulation with allogenic target cells. The lytic proteins are stored in the secretory granules which are released after cross-linking of the T cell receptor (TcR) upon target cell recognition. During lytic granule biogenesis granzyme A protein synthesis can be detected between 2 and 10 days after allogenic stimulation of the CTL. Although granzyme A is stored in the lytic granules over this period, the majority of granzyme A synthesized is secreted directly from the CTL. TcR triggering of degranulation also results in new synthesis of the lytic proteins, which can be inhibited by cycloheximide (CHX). Some of the newly synthesized lytic proteins can be stored in the cell and refill the granules. But up to one third of granzymes A and B can be secreted directly from the CTL via the constitutive secretory pathway as shown by granzyme A enzymatic activity and immunoblots of secreted granzyme B, where one third of the protein fails to acquire the granule targeting signal. Perforin is also secreted via the constitutive pathway, both from the natural killer cell line, YT, and from CTL clones after TcR cross-linking. Constitutive secretion of the lytic proteins can be blocked by both CHX and brefeldin A (BFA). While BFA does not affect the directional killing of recognized targets, it abrogates bystander killing, indicating that bystander killing arises from newly synthesized lytic proteins delivered via a non-granule route. These results demonstrate that the perforin/granzyme-mediated lytic pathway can be maintained while CTL kill multiple targets. We show that CTL not only re-fill their granules during killing, but also secrete lytic proteins via a non-granule-mediated pathway.
KW - Cytotoxic T lymphocytes
KW - Granzymes
KW - Killing
KW - Perforin
KW - Secretion
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U2 - 10.1002/eji.1830250432
DO - 10.1002/eji.1830250432
M3 - Article
C2 - 7737276
AN - SCOPUS:0028914352
VL - 25
SP - 1071
EP - 1079
JO - European Journal of Immunology
JF - European Journal of Immunology
SN - 0014-2980
IS - 4
ER -