Effects of Selenium and Thyroid Hormone Deficiency on Peritoneal Macrophages Adhesion and Occurrence of Natural IGM Antibodies in Juvenile Rats

Both selenium, as an effector and regulator of antioxidative enzymes activity, and thyroid hormones are potent immunomodulators. Besides, selenium incorporated into iodothyronine deiodinases is involved in the thyroid function and thus indirectly regulates the immune response. Studies of the mutual influence of selenium and thyroid hormones on the immune response are scarce, hence we analyzed the effects of an iodothyronine deiodinases blocker, propylthiouracil (PTU), and selenium deficiency on the function of peritoneal macrophages, and titer of naturally occurring anti-sheep red blood cells (SRBC) IgM antibodies in juvenile rats. The experiment was carried out on 64 Wistar male rats allotted to 4 groups: controlselenium adequate PTU_- group; selenium adequate, PTU+ group; selenium defi cient, PTU_- group; and selenium defi cient, PTU+. The selenium adequate and selenium defi cient groups were fed a diet containing 0.334 and 0.031 mg Se/kg, respectively. PTU+ groups received PTU (150 mg/L) in drinking water. After 3 weeks, thyroxine (T₄), triiodothyronine (T₃), and thyroid stimulating hormone (TSH) were determined. The animals having “intermediate” concentrations of T₃ (1.56-1.69 nmol/L) and T₄ (41-50 nmol/L) were excluded from further analysis. Thus, PTU+ groups included hypothyroid animals (T₃≤1.55 nmol/L; T₄≤40 nmol/L), while PTU_- groups included euthyroid rats (T₃≥1.70 nmol/L; T₄≥50 nmol/L). Both groups of selenium deficient rats had, when compared to the control group, a significantly lower activity of glutathione peroxidase GPx1 and GPx3. Neither selenium deficiency nor PTU influenced the adherence of peritoneal macrophages. Selenium deficiency significantly decreased the peroxide synthesis in macrophages and significantly increased the titer of anti-SRBC IgM. Hypotyroidism alone or in combination with selenium deficiency had no influence on these parameters.