Immunophenotyping of peripheral blood lymphocytes at children and adolescents with Hashimoto's thyroiditis

Two-color immunophenotyping of lymphocyte subsets using a lysed whole blood method was performed in 46 children and adolescents with Hashimoto's thyroiditis (HT) from contaminated areas and in 18 children from 'clean' areas of Belarus. 46 healthy children of matched age and sex distribution were used as control group. Analysis of lymphocyte subsets in children with HT living in contamination areas shower a considerable decrease in the levels of total lymphocytes, CD8+ T cells (T-suppressors), total B cells, and CD5+ B cells together with an activation of NK and CD56+, CD8+CD57+T cells (T-killers not restricted by HLA antigens). The study of cellular immunity in children with different doses of ionizing radionuclides revealed that prolonged influence of very small doses of ionizing radiation resulted in significant changes in lymphocyte subsets; interestingly, B cell subsets were the first to react to such influence while stability of T-killers and NK was the highest. These changes were the greatest in children with HT with the highest dose of incorporated radionuclides. Significant correlation between the levels of main lymphocyte subsets and the doses of accumulated radionuclides observed in this study also indicated that their relation was dose-dependent. The results of the study suggest that 1) lymphocyte subsets are different in their reaction to chronic internal irradiation which, evidently, is determined by their proliferation activity, degree of differentiation, and function; 2) increase in the dose of incorporated radionuclides in children and adolescents with HT leads to different reaction of sells- a decrease in T-suppressors, B cells and activation of cells responsible for nonspecific cytotoxicity- T-killers unrestricted by HLA antigens and NK; 3) children and adolescents with HT from contaminated regions have much more pronounced imbalance of cellular immunity and activation of cellular cytotoxic reactions damaging the thyroid tissue than those with HT from 'pure' regions. (authors) 1 fig., 3 tabs., 17 refs