Influence of continuous, very low-dose gamma-irradiation on the mouse immune system.
OBJECTIVE
To investigate whether continuous, very low-dose gamma-irradiation (10 cGy/year) modifies immune parameters in mice.


METHODS
C57BL/6 female mice, 4 weeks old, were irradiated for 24 months and compared with control mice living in the same room. B- and T-cell subsets were evaluated by flow cytometry before and after stimulation with lectins; subclasses of immunoglobulins were determined by ELISA 2, 4, 6, 8, 12, 18 and 24 months after the beginning of the irradiation.


RESULTS
No difference was found in the percentage of CD4(+) and CD8(+) cells in the thymus and the spleen, or in the reactivity of T-cells to lectins. While the number of B-cells in the spleen remained unchanged, a significant decrease of IgG1, IgG2b and IgG2a was observed after respectively 12, 18 and 24 months of irradiation.


CONCLUSIONS
The parameters of cellular immunity studied were not affected by this chronic low-dose of irradiation, but this dose rate is probably too low to induce the hormetic effect previously described. Further investigations are necessary to assess whether the decline of immunoglobulin secretion is indicative of a lower rate of infectious diseases or a defect in B-cell function.
Courtade
M
M
Laboratoire d'Histologie-Embryologie, Faculté de Médecine Toulouse-Rangueil, 133, route de Narbonne, 31062 Toulouse Cedex, France. courtade@cict.fr
Caratero
A
A
Jozan
S
S
Pipy
B
B
Caratero
C
C
D000818:Animals; D000917:Antibody Formation / Q000528:radiation effects*; D001402:B-Lymphocytes / Q000276:immunology / Q000528:radiation effects; D016516:CD4-CD8 Ratio; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005720:Gamma Rays; D007111:Immunity, Cellular / Q000528:radiation effects*; D007070:Immunoglobulin A / Q000276:immunology / Q000378:metabolism / Q000528:radiation effects; D007074:Immunoglobulin G / Q000276:immunology / Q000378:metabolism / Q000528:radiation effects; D008213:Lymphocyte Activation / Q000276:immunology / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000528:radiation effects; D013601:T-Lymphocytes / Q000276:immunology / Q000528:radiation effects; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology / Q000528:radiation effects; D013997:Time Factors
D007070:Immunoglobulin A; D007074:Immunoglobulin G