The acute effects of proton whole-body irradiation (WBI) on leukocytes, lymphocytes, and hematological parameters in the spleen and blood of C57BI/6 mice were examined and compared to the effects of photon (gamma) WBI derived from a 60cobalt (60Co) source. Adult, female C57BL/6 mice were exposed to a single dose (3 Gy, 0.4 Gy/min dose rate) of either proton WBI at the Bragg peak, proton WBI at the entry plateau, or Co WBI, and sacrifice intervals were at 1,4, 7, and 10 days post- WBI. Flow cytometry analysis of the spleen and peripheral blood showed depression in cell counts for all time points when compared to the non-irradiated control group. B (CD19+) and T-cytotoxic/suppressor (CD3+CD8+) lymphocytes were the most radiosensitive, while natural killer (NK1.1+) cells were the most radioresistant. Splenic T cells showed reduced responsiveness to mitogen stimulation for the first four days post- WBI, while splenic B cell responsiveness was reduced at all time periods. Analysis of hematological parameters showed depression of red blood cells, hemoglobin concentration, and hematocrit levels after 4 days post-WBI; platelet counts were low at days 4 and 10. Comparison of the proton and 60Co-irradiated groups showed few statistically significant differences among the radiation groups at any time point. These data indicate, for the very first time, that cells of the immune system are affected similarly by 3 Gy proton (Bragg peak and entry plateau) and gamma WBI. These findings could have a significant impact on future studies designed to maximize normal tissue protection during and after proton radiation exposure.

Key words: Leukocytes, lymphocyte subsets, radiation, protons, whole-body

LLU Discipline

Microbiology and Molecular Genetics




Graduate School

First Advisor

Daila S. Gridley

Second Advisor

Carlos A. Casiano

Third Advisor

John E. Lewis

Fourth Advisor

Greg A. Nelson

Degree Name

Master of Science (MS)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Radiation Effects; Spectrometry, X-Ray Emission; Radiation Genetics; Immune System



Page Count

vii; 37

Digital Format


Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


Loma Linda University Electronic Theses and Dissertations

Collection Website



Loma Linda University. Del E. Webb Memorial Library. University Archives