Expression of interleukin-4 in apoptotic cells: stimulation of the type-2 cytokine by different toxins in human peripheral blood mononuclear and tumor cells.
BACKGROUND
Immunological reactivity is regulated by T-cell populations (type-1 and type-2 cells) via cytokine secretion, but their influence on apoptosis remains unclear.


METHODS
Intracellular expression of type-1 (interferon [IFN]-gamma) and type-2 (interleukin [IL]-4) cytokines and apoptosis-related molecules (Apo2. 7, Bcl-2 protein) was studied by flow cytometry in human peripheral blood mononuclear cells (PBMC), myeloma (U-266), monocytic (THP-1), and T-leukemia cells (MOLT-4) in response to toxins, which act on different intracellular targets (actinomycin D, cycloheximide, the mistletoe lectins [ML]-1 and ML-3, brefeldin A, staurosporine).


RESULTS
The apoptosis-inducing toxins stimulated intracellular IL-4 expression mainly in PBMC with high expression of the mitochondrial apoptosis marker, Apo2.7, but with decreased level of the anti-apoptotic Bcl-2 protein. Up-regulation of IL-4 coincided with a significant down-regulation of IFN-gamma in CD4(+) and CD8(+) cells. The inhibitor of oxidative phosphorylation, oligomycin, and the caspase inhibitor, z-VAD-fmk, abolished IL-4 expression and DNA fragmentation in the PBMC. Also in the myeloma, monocytic, and T-leukemia cells, IL-4 was mainly observed in the Apo2.7(+) apoptotic cells in response to the toxins.


CONCLUSIONS
We suggest that the different apoptotic toxins activate a common pathway in which IL-4 production plays a yet unknown intracellular role further downstream during apoptosis.
Stein
G M
GM
Krebsforschung Herdecke, Department of Applied Immunology, University Witten/Herdecke, Communal Hospital, Herdecke, Germany. stein.g@debitel.net
Pfüller
U
U
Schietzel
M
M
Büssing
A
A
D017209:Apoptosis / Q000187:drug effects*; D020126:Brefeldin A / Q000494:pharmacology; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D053938:DNA Fragmentation / Q000187:drug effects; D003609:Dactinomycin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D020287:In Situ Nick-End Labeling; D007371:Interferon-gamma / Q000096:biosynthesis / Q000378:metabolism / Q000494:pharmacology; D015847:Interleukin-4 / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010085:Oxidative Phosphorylation / Q000187:drug effects; D028321:Plant Preparations; D010940:Plant Proteins; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D054790:Ribosome Inactivating Proteins, Type 2; D019311:Staurosporine / Q000494:pharmacology; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D014118:Toxins, Biological / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D028321:Plant Preparations; D010940:Plant Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D054790:Ribosome Inactivating Proteins, Type 2; D014118:Toxins, Biological; C009674:ribosome inactivating protein, Viscum; D003609:Dactinomycin; D020126:Brefeldin A; D015847:Interleukin-4; D007371:Interferon-gamma; D003513:Cycloheximide; D020169:Caspases; D019311:Staurosporine