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KMID : 0350519950480041145
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Journal of Catholic Medical College
1995 Volume.48 No. 4 p.1145 ~ p.1158
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The Influence on Natural Killer Cell Mediated Cytotoxicity and T-Lymphocyte Subpopulations in BALB/c Mouse with Sarcoma- 180 by Fractionated Low-Dose Whole-Body Radiation
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Abstract
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The stimulatory response induced by an exposure to a low dose of an otherwise boxic agent has been known for cver a century, and observed in a wide variety of organisms, ranging from the bacteria to mammals. However the mechanism responsible for
such
phenomenon is not clear. More recently, radiation, in relativeiy lower dose, has also been related with augmented immune responses, the basic information of which is junavailable either.
The present experimental study has been carried out to determine whether a low-dose whole-body radiation is to the benefit or detriment of host immune function by analyzing the effects of such a radiation on various functions including natural
killer
cell (NK cell) mediated cytotoxicity, T-lymphocyte subpopulations. One hundred and fifty BALB/c mice were used for the study. The experiment groups consisted of control group (no tumor), sham irrdiated tumor group (tumor without radiation) and
irradiated tumor group (tumor with radiation). Malignant tumor was produced in the right thigh of mice by the innoculation of mouse sarcoma-180 tumor cells. Five cGy of radiation from a 6-MV linear accelerator was administered every other day
from
2
days after innoculation to 20 days. NK cell inediatded cytotoxicity was determined by the standard 4-h chromium release assay using K-562 human erythroleukemic cells every 10 cGy of accumulated radiation dose. At the same time the percentage of
the
CD3
positive lymphocytes, CD4 positive lymphocytes and CD8 positive lymphocytes and the CD4/CD8 ratio were counted and calculated, respectivel, by immunofluoresecnt antibody techniquen. The tumor in the mouse thigh was evaluated microscopically by
hematoxylin-eosin stain (H-E stain) and immunofluoresent antibody technique.
@ES The results obtained were summarized as follows :
@EN 1. The NK cell mediated cytotoxicity of the irradiated tumor group was significantly higher at all doses above 10 cGy than the other two groups (p<0.05). The difference between sham irradiated tumor group and irradiated tumor group at 30 cGy
was
stutistically not significant. The NK cell mediated cytotoxicity of the irradiated tumor group started to increse at the dose of 10 cGy and reached the peak at the dose of 40 cGy.
2. The percentages of the T-lymphocyte subpopulations (CD3 positive lymphocytes, CD4 positive lymphocytes, CD8 positive lymphocytes) in the sham irradiated tumor group and irradiated tumor group increased significantly compared to the control
group at
all doses (p<0.01), and the CD4/CD8 ratio in the irradiated tumor group also incresed significantly compared to the control group at 20 cGy, 30 cGy (p<0.01).
3. Histology showed more prominent lymphocytic infiltration around the tumor in the irradiated tumor group than in the sham irradiated tumor group. And the more CD3 positive lymphocytes, CD4 positive lymphocytes, CD8 positive lymphocytes were
detected
around the tumor in the irradiated tumor group than in the sham irradiated tumor group by the immunofluoresent antibody technique.
The above results suggest that cellular immunity can be potentiated by the exposure of mouse to a low-dose whole-body radiation of 5 cGy with an accumulated dose of 50 cGy. Our observation may form a ground on which future treatment of malignant
tumors
can be based.
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