Vitamin E and beta-carotene affect natural killer cell function.
Vitamin E supplementation has been shown to contribute in immunoregulation, antibody production, and resistance to implanted tumors. Similarly beta-carotene has been shown to down-regulate growth factors which contribute towards proliferation of pre-malignant cells. We embarked upon a study to evaluate the effect of vitamin E and beta-carotene on natural killer (NK) cells, which perform tumor surveillance role in the mammalian body. Mouse splenocytes or human peripheral blood lymphocytes were used as NK cells with murine YAC-1 lymphoma or human K-562 lymphoma cells, respectively, as target cells. The NK cells were treated with vitamin E or beta-carotene while target cells were labeled with sodium 51chromate. Both cell types were then reacted for 4 hours. The NK cell tumorolytic activity was measured by the chromium release assay. Oral administration of alpha-tocopherol at a dose of 100 mg/d in mice showed a significant increase in NK cell activity. Similarly, treatment of NK cells with alpha-tocopherol in vitro at doses 0.5 mg/ml, 1-0 mg/ml, and 2.0 mg/ml increased the tumorolytic activity of NK cells. Tocotrienol showed a similar response at ten times lower dose. When NK cells were treated with varying concentrations of palm vitee (mixture of alpha-tocopherol and tocotrienol), maximum effect was observed at the dose mixture of 12 micrograms and 24 micrograms alpha-tocopherol and tocotrienol, respectively. When murine NK cells were treated in vitro with beta-carotene at doses ranging from 2 ng/mg to 200 ng/ml, a decrease in tumorolytic effect was observed. However, human NK cells after treatment with beta-carotene at doses ranging from 0.1 microgram/ml to 10 micrograms/ml showed a significant increase in tumorolytic function. NK cells were also obtained from mice that had been parenterally administered beta-carotene and alpha-tocopherol. These experiments showed no significant increase in the NK cell function.
Department of Biochemistry, Aga Khan University, Stadium Road, PO Box 3500, Karachi, Pakistan.
M K
MK
Ashfaq
H S
HS
Zuberi
M
M
Anwar Waqar
D000818:Animals; D002860:Chromium Radioisotopes; D006801:Humans; D007694:Killer Cells, Natural / Q000187:drug effects* / Q000502:physiology; D008214:Lymphocytes / Q000502:physiology; D008223:Lymphoma / Q000188:drug therapy / Q000503:physiopathology; D051379:Mice; D008807:Mice, Inbred BALB C; D013154:Spleen / Q000166:cytology; D014407:Tumor Cells, Cultured; D014810:Vitamin E / Q000494:pharmacology* / Q000502:physiology; D019207:beta Carotene / Q000494:pharmacology* / Q000502:physiology
D002860:Chromium Radioisotopes; D019207:beta Carotene; D014810:Vitamin E