Impaired regulation of immune cells with low doses of radiation exposure: Possible connection to allergy development

Abstract Rationale Dysregulation of immune the system under radiation exposure leads to improper activation of T-cell subpopulations which may result in chronic infections or allergic diseases. The aim of this research was to study the connection between immune cell genome damage and allergy development in children from contaminated areas of Belarus. Methods 200 children aged 5-15 living in areas contaminated with Cs 137 were examined repeatedly (2002-2003). The examination included DNA breakage determination in lymphocytes by a "fast micromethod" and immunophenotype evaluation by flow cytometry. Children examined were grouped (1-4) by Cs 137 ground contamination (2-5, 7-10, 13-16 and above 16 Ci/km 2 respectively). Results Low doses of radiation increased DNA breakage in immune cells related to Cs 137 exposure, correlating positively to CD95 expression and negatively to CD4+CD25+ cell content in peripheral blood. The amount of CD4+CD25+ suppressor cells changed with Cs 137 ground contamination. Occurrence of chronic infections (43.3%, 35.2%, 23.3% and 27.4% children in groups 1-4) and allergic disorders (16.0%, 44.9%, 7.1% and 13.3% in groups 1-4) was influenced by these immune changes. Conclusions Low doses radiation caused DNA damage, which resulted in an initial increase and later decrease of suppressor CD4+CD25+ cell levels related to Cs 137 soil contamination. Changes in CD4+CD25+ cell levels were associated with chronic infections in children, while CD4+CD25+ cell changes were associated with allergy development.