Effect of chronic exposure on the concentration of NF-κB in peripheral blood lymphocytes

BACKGROUND: The importance of this study is entrenched in the possibility that alterations in NF-κB-mediated intracellular signaling pathways could serve as the foundation for some pathogenetic mechanisms of radiation-induced carcinogenesis in chronically exposed individuals.

AIM: The objective of the study was to analyze the concentration of NF-κB transcription factor in lysates of peripheral blood lymphocytes of individuals exposed to chronic radiation during the implementation of carcinogenic effects of exposure.

MATERIAL AND METHODS: The study is applied analytically one time. 50 chronically exposed individuals were examined, whose average age was 73.7 years. The average accumulated radiation dose to the red bone marrow was 727.9±79.1 mGy; the average accumulated exposure dose to the thymus and peripheral lymphoid organs was 85.9±13.6 mGy. Participants from the main group were divided into three subgroups (n=18, n=16, n=16) depending on on the radiation dose (0.07–0.44 Gy; 0.45–0.84 Gy; 0.85–2.93 Gy respectively).

The difference between the comparison group and the main group in terms of age, sex, and ethnic composition was not statistically significant; also, an inclusion of 25 individuals who were not accidentally exposed was made. The intracellular concentration of NF-κB was ascertained by enzyme immunoassay in protein concentration-normalized (500 μg/mL) lysates of peripheral blood lymphocytes. Statistical data processing employed descriptive statistical methods, as well as Kolmogorov–Smirnov test, Student's t-test, Wilcoxon–Mann–Whitney U-test, Jonсkheere–Terpstra test, and Spearman correlation analysis.

RESULTS: The median concentration of NF-κB in the main group was 34.5 pg/ml, and in the comparison group — 28.1 pg/ml. The differences in the indices in individuals from the main group relative to the comparison group were not statistically significant (р=0.360), as well as between different dose groups: 0.07–0.44 Gy — 31.5 pg/ml and 0.45–0.84 Gy — 32.4 pg/ml (р=0.431); 0.45–0.84 Gy — 32.4 pg/ml and 0.85–2.93 Gy — 38.5 pg/ml (р=0.692), 0.07–0.44 Gy and 0.85–2.93 Gy (р=0.534). No statistically significant differences were found between the dose groups and the comparison group (р=0.931). No dependences of NF-κB concentration on the exposure dose to the red bone marrow, thymus, and peripheral lymphoid organs, age, sex, and ethnicity of the examined individuals were detected.

CONCLUSION: The intracellular concentration of the transcription factor NF-κB does not differ significantly in individuals exposed to chronic radiation and individuals who were not accidentally exposed. Results indirectly confirm the involvement of NF-κB-mediated signaling pathways in the implementation of adaptive responses of the human body to chronic low-intensity radiation exposure.