Radiation-induced bystander effect in immune response.
OBJECTIVE
Since most reports on bystander effect have been only concerned with radiation-induced damage, the present paper aimed at disclosing whether low dose radiation could induce a stimulatory or beneficial bystander effect.


METHODS
A co-culture system containing irradiated antigen presenting cells (J774A.1) and unirradiated T lymphocytes (EL-4) was established to observe the effect of J774A.1 cells exposed to both low and high doses of X-rays on the unirradiated EL-4 cells. Incorporation of 3H-TdR was used to assess the proliferation of the EL-4 cells, expression of CD80/86 and CD48 on J774A.1 cells was measured with immunohistochemistry and flow cytometry, respectively. NO release from J774A.1 cells was estimated with nitrate reduction method.


RESULTS
Low dose-irradiated J774A.1 cells could stimulate the proliferation of the unirradiated EL-4 cells while the high dose-irradiated J774A.1 cells exerted an inhibitory effect on the proliferation of the unirradiated EL-4 cells. Preliminary mechanistic studies illustrated that the differential changes in CD48 expression and NO production by the irradiated J774A.1 cells after high and low dose radiation might be important factors underlying the differential bystander effect elicited by different doses of radiation.


CONCLUSIONS
Stimulatory bystander effect can be induced in immune cells by low dose radiation.
Liu
Shu-Zheng
SZ
Department of Radiation Biology, Jilin University School of Public Health, 8 Xinmin Street, Changchun 130021, Jilin, China.
Jin
Shun-Zi
SZ
Liu
Xiao-Dong
XD
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000378:metabolism / Q000528:radiation effects*; D015703:Antigens, CD / Q000276:immunology; D018122:B7-1 Antigen / Q000276:immunology; D051940:B7-2 Antigen; D024201:Bystander Effect / Q000528:radiation effects*; D002455:Cell Division / Q000276:immunology; D002460:Cell Line; D018920:Coculture Techniques; D004307:Dose-Response Relationship, Radiation; D008562:Membrane Glycoproteins / Q000276:immunology; D051379:Mice; D009569:Nitric Oxide / Q000096:biosynthesis; D013601:T-Lymphocytes / Q000276:immunology*; D014965:X-Rays
D015703:Antigens, CD; D018122:B7-1 Antigen; D051940:B7-2 Antigen; C497965:Cd86 protein, mouse; D008562:Membrane Glycoproteins; D009569:Nitric Oxide