Granule exocytosis, and not the fas/fas ligand system, is the main pathway of cytotoxicity mediated by alloantigen-specific CD4(+) as well as CD8(+) cytotoxic T lymphocytes in humans.
We investigated the cytotoxicity mechanisms of alloantigen-specific human CD4(+) and CD8(+) cytotoxic T lymphocytes (CTLs) using cells from family members with the Fas gene mutation. Alloantigen-specific CD4(+) and CD8(+) CTL bulk lines and clones were generated from 2 individuals by stimulation of their peripheral blood lymphocytes with allogeneic Fas(-/-) or Fas(+/-) cell lines that were established from B-lymphocytes of a patient with Fas deficiency and her mother, respectively. Both CD4(+) and CD8(+) CTL bulk lines and clones directed against allogeneic HLA antigens exerted cytotoxicity against Fas(-/-) and Fas(+/-) cells to almost the same degree. The cytotoxicity of CD4(+) and CD8(+) CTLs appeared to be Ca(2+)-dependent and was completely inhibited by concanamycin A, an inhibitor of perforin-mediated cytotoxicity. Messenger RNAs for the major mediators of CTL cytotoxicity, Fas ligand, perforin, and granzyme B were all detected in these CD4(+) CTLs with the use of the reverse transcriptase polymerase chain reaction. The majority of CD4(+) CTL clones that showed Fas-independent cytotoxicity were T(H)0, as determined by their cytokine production profile. These data, obtained with the use of a novel experimental system, clearly show that the main pathway of cytotoxicity mediated by alloantigen-specific human CD4(+) as well as by CD8(+) CTLs is granule exocytosis, and not the Fas/Fas ligand system.
Yasukawa
M
M
First Department of Internal Medicine, Ehime University School of Medicine, Shigenobu, Ehime. yasukawa@m.ehime-u.ac.jp
Ohminami
H
H
Arai
J
J
Kasahara
Y
Y
Ishida
Y
Y
Fujita
S
S
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002460:Cell Line; D003594:Cytoplasmic Granules / Q000502:physiology*; D003602:Cytotoxicity, Immunologic; D004533:Egtazic Acid / Q000494:pharmacology; D005089:Exocytosis; D053222:Fas Ligand Protein; D053804:Granzymes; D006801:Humans; D007519:Isoantigens / Q000276:immunology; D018942:Macrolides; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012697:Serine Endopeptidases / Q000235:genetics; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D019014:fas Receptor / Q000235:genetics / Q000502:physiology*
D000900:Anti-Bacterial Agents; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D007519:Isoantigens; D018942:Macrolides; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D012333:RNA, Messenger; D019014:fas Receptor; D054353:Perforin; D004533:Egtazic Acid; C036978:concanamycin A; C509213:GZMB protein, human; D053804:Granzymes; D012697:Serine Endopeptidases