Low dose radiation induced immunomodulation: effect on macrophages and CD8+ T cells.
OBJECTIVE
The aim of the present investigation was to study the effect of fractionated whole body low dose ionizing radiation (LDR) on the functional responses of T lymphocytes, their subpopulations and macrophages.


METHODS
C57BL/6 mice were exposed to 4 cGy from a (60)Co source, at 0.31 cGy/min, at 24 h intervals for 5 days (total dose 20 cGy). Phagocytic activity was measured by flow cytometry using Bioparticles and nitric oxide generation was estimated by spectrophotometry. Proliferation of lymphocytes in response to concanavalin A (con A) and alloantigens was measured by (3)H thymidine incorporation. Expression of cell surface markers was assessed by flow cytometric analysis of antibody labeled cells. Target cell killing by cytotoxic T cells (CTL) generated against allogenic cells was assessed by flow cytometry using PKH26 labeled target cells. Cytokines were estimated by enzyme linked immunosorbent assay.


RESULTS
Exposure to LDR enhanced nitric oxide secretion and phagocytosis. The expression of early activation antigen, CD69, was enhanced in CD8(+) T lymphocytes concomitant with enhanced proliferation in response to con A. In addition, mixed lymphocyte reaction (MLR) and CTL response were augmented and secretion of interferon gamma (IFN-gamma) was suppressed following LDR exposure.


CONCLUSIONS
LDR exposure enhanced the function of macrophages and responses of CD8(+) T cells in C57BL/6 mice.
Radiation Biology and Health Sciences Division, Bioscience Group, Bhabha Atomic Research Centre, Modular Laboratories, Trombay, Mumbai, India.
Ruchi
R
Pandey
Bhavani S
BS
Shankar
Deepak
D
Sharma
Krishna B
KB
Sainis
D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000528:radiation effects*; D002478:Cells, Cultured; D016207:Cytokines / Q000276:immunology*; D005260:Female; D007155:Immunologic Factors / Q000276:immunology; D008264:Macrophages / Q000276:immunology* / Q000528:radiation effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000276:immunology; D010587:Phagocytosis / Q000276:immunology / Q000528:radiation effects*; D011829:Radiation Dosage; D014916:Whole-Body Irradiation / Q000379:methods*
D016207:Cytokines; D007155:Immunologic Factors; D009569:Nitric Oxide