Modulation of mononuclear phagocyte cytotoxicity by alpha-tocopherol (vitamin E).
The in vitro effect of colloidal suspensions of alpha-tocopherol (alpha-T) on phorbolmyristate-acetate (PMA)-induced monocyte cytotoxicity and on antibody-dependent monocyte cytotoxicity (ADCC) was studied. We observed that 1) in the presence of alpha-T, the inhibition was twice as high in the PMA-induced assay than in ADCC; 2) monocytes preincubated with alpha-T were inhibitory in both assays but much less in ADCC, and 3) target erythrocytes preincubated with alpha-T decreased the cytotoxicity in the PMA-induced assay only. Since alpha-T preincubated monocytes showed a decreased release of H2O2 but not of O2-, we concluded that one of the mechanisms by which alpha-T decreased cytotoxicity could be decreased release of H2O2. Whereas the role of H2O2 was documented in the PMA-induced cytotoxicity, in ADCC non-oxidative injury seems more important. This is supported by 1) lesser inhibition of the assay with alpha-T preincubated monocytes; 2) lack of protection with alpha-T preincubated erythrocytes, and 3) mild inhibition with protease inhibitor.
Leb
L
L
Beatson
P
P
Fortier
N
N
Newburger
P E
PE
Snyder
L M
LM
D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D004912:Erythrocytes / Q000276:immunology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology*; D009000:Monocytes / Q000187:drug effects / Q000276:immunology*; D013481:Superoxides / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014810:Vitamin E / Q000494:pharmacology*
D013481:Superoxides; D014810:Vitamin E; D006861:Hydrogen Peroxide; D013755:Tetradecanoylphorbol Acetate