Effects of proton and gamma radiation on lymphocyte populations and acute response to antigen.
BACKGROUND
The clinical use of proton radiation in the management of cancer, as well as benign disorders, is rapidly increasing. The major goal of this study was to compare the effects of proton and gamma (60Co) radiation on cell-mediated and humoral immunological parameters.


METHODS
C57BL/6 mice were exposed to a single dose of 3 Gray (Gy) protons or gamma-rays and intraperitoneally injected 1 day later with sheep red blood cells (sRBC). On 4, 10, 15, and 29 days after exposure, subsets from each group were euthanised; nonirradiated controls (with and without sRBC injection) were included. Body and relative spleen weights, leukocyte counts, spontaneous blastogenesis, lymphocyte populations, and anti-sRBC titers were evaluated.


RESULTS
The data showed significant depression (p < 0.05) in nearly all assays on days 4 and 10 after irradiation. B lymphocytes (CD19+) were the most radiosensitive, although reconstitution back to normal levels was observed by day 15. T cell (CD3+) and T helper cell (CD4+) recovery was evident by day 29, whereas the T cytotoxic cell (CD8+) count remained significantly below normal. Natural killer cells (NK1.1+) were relatively radioresistant. Anti-sRBC antibody production was slow and low titers were obtained after irradiation. No significant differences were noted between the two types of radiation.


CONCLUSIONS
Taken together, the data show that whole-body irradiation with protons or gamma-rays, at the dose employed, results in marked, but transient, immunosuppression. However, at the time points of testing and with the assays used, little or no differences were found between the two forms of radiation.
Kajioka
E H
EH
Department of Radiation Medicine (Radiobiology Program), Loma Linda University School of Medicine, CA 92354, USA.
Gheorghe
C
C
Andres
M L
ML
Abell
G A
GA
Folz-Holbeck
J
J
Slater
J M
JM
Nelson
G A
GA
Gridley
D S
DS
D000818:Animals; D000906:Antibodies / Q000097:blood; D000954:Antigens, Surface / Q000494:pharmacology*; D001402:B-Lymphocytes / Q000166:cytology / Q000528:radiation effects; D016516:CD4-CD8 Ratio; D003035:Cobalt; D004912:Erythrocytes / Q000276:immunology*; D005720:Gamma Rays; D016130:Immunophenotyping; D007958:Leukocyte Count; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009929:Organ Size / Q000528:radiation effects; D011522:Protons; D012756:Sheep; D013154:Spleen / Q000528:radiation effects
D000906:Antibodies; D000954:Antigens, Surface; D011522:Protons; D003035:Cobalt