Fas/FasL-independent activation-induced cell death of T lymphocytes from HIV-infected individuals occurs without DNA fragmentation.
We assessed the effects of activation with phorbol myrystic acetate (PMA) and ionomycin on peripheral blood mononuclear cells (PBMC) from HIV-infected individuals by (51)Cr release, propidium iodide (PI) uptake, electron microscopy, and DNA analysis. Up to 70% (51)Cr release was induced from PBMC of HIV-infected individuals, versus up to 26% (51)Cr release from PBMC of non-HIV-infected volunteers. Flow cytometry identified mostly T cells undergoing activation-induced cell death (AICD). The kinetics of (51)Cr release and the effects of cold target inhibitors were consistent with cell-mediated cytotoxicity. Certain anti-CD3 antibodies or extracellular Ca(2+) chelation prevented AICD, but antagonistic anti-Fas antibodies, caspase inhibitors, and cycloheximide had no effect. The antioxidants thiourea and N-acetylcysteine reduced AICD, indicating a role for oxidative stress. Electron microscopy revealed plasma membrane disruption with nuclear integrity, while DNA analysis showed intact chromosomal DNA. This form of T cell AICD triggered by PMA and ionomycin differs from classical apoptosis in the absence of either caspase involvement or DNA fragmentation.
Kottilil
S
S
Immunology Program, Memorial University of Newfoundland, Canada.
Bowmer
M I
MI
Trahey
J
J
Howley
C
C
Gamberg
J
J
Grant
M D
MD
D000111:Acetylcysteine / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism; D016923:Cell Death; D002478:Cells, Cultured; D002860:Chromium Radioisotopes; D053938:DNA Fragmentation; D053222:Fas Ligand Protein; D005434:Flow Cytometry; D015658:HIV Infections / Q000276:immunology* / Q000473:pathology; D006801:Humans; D016130:Immunophenotyping; D015759:Ionomycin / Q000494:pharmacology; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000502:physiology*; D016176:T-Lymphocyte Subsets / Q000145:classification; D013601:T-Lymphocytes / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013890:Thiourea / Q000494:pharmacology; D019014:fas Receptor / Q000502:physiology*
D000975:Antioxidants; D002860:Chromium Radioisotopes; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D019014:fas Receptor; D015759:Ionomycin; D020169:Caspases; D013890:Thiourea; D013755:Tetradecanoylphorbol Acetate; D000111:Acetylcysteine